Fuel Gauge Fault - Fixed! Plus Ext. Temp/Time/Volts Display!

Laird Scooby · Nov 22nd, 2019, 08:51

We all know the fuel gauges on the 7/9xx are prone to not working or only working intermittently. Since i got my current 760, the gauge has had the work ethics of a 1970s coal miner. My previous 740 was the same and i designed and built an LED bargraph gauge for that :

Having done various tests on my 760, i had come to the conclusion that wasn't an option. The fault appeared to lie somewhere between the gauge and the car wiring - that left the PCB on the back of the instrument cluster.

Looking at that, at first glance it looks like an explosion in a spaghetti factory but delving in, i made some sense out of it. The 3-pole connector on the PCB centre-top is +ve, -ve and speedo signal. This also provides the +ve feed for the rest of the cluster including warning lamps, speedo and temp gauge.
You'd think if the fuel gauge was dropping out, the rest would as well? In several cases you'd be right but have a look at these pics :

This is a close up of 3 out of the 4 solder pad connections near the PCB fuse to the left. at the top. They weren't great and using the continuity tester on my multimeter, i could switch the buzzer in it on and off by wiggling the PCB around the fuse area.
As such, these 4 pads were my first port of call for repair. Smeared a little soldering flux on them, heated them up with the iron and removed the old solder with a solder-sucker.
A little more soldering flux then resoldered with some new real solder - that's most of the problem, the original isn't proper solder!

Thanks to the EU, back in the mid-late 80s, leaded solder in the workplace was outlawed by the EU - the lead-free replacement does NOT stand the test of time!

I also added an aftermarket clock/internal & external temperature display/voltmeter, picking up the +ve feed from the back of the fuel gauge and the -ve from the electronic rheostat for the panel lighting on the back of the cluster. I need to make a proper bracket for the display module and find better places for the temperature sensors (they can give some strange readings at present due to their locations!

) but here's the module fitted to the cluster :

After repairing theose 4 solder pads, i was hopeful i'd cracked it, especially as i'd been able to make at least one of them act as a switch!

However, testing in the car proved me wrong, although for the first 10 minutes i thought i'd done it. Then the fuel gauge dropped like a stone and the display disappeared from the module.
This was incredibly useful in diagnostic terms. It left two more solder pad connections that were potentially the source of the fault.

The one just underneath the indicator tell-tale and the one the other end of the dotted line from it. These two in fact :

Left hand pad, near the tell-tale. 'orrible, ain't it?

Pad t'other end of the dotted line, not much better!

After removing old solder and applying new!

Refitted the cluster yesterday morning and had to go shopping which gave it a reasonably long test - all good thankfully, despite doing everything i could to make it fault! I'd previously worked out that if the gauge worked from cold, once i got some warmth in the car, it would die. Conversely if it didn't work from cold, by getting some warmth into the car, i could make it work - turning the heat down after this would cause it to drop out again. None of these things effect it now thankfully!

Also a short vid of the module in operation :

https://youtu.be/qe5B09I4BYk

One of the temperature sensors is tucked onto a clip on the back of the instrument cluster so gets all the heat from the footwell and any heat from the cluster, the other goes into the engine bay then onto the plenum cover over the wiper mech under the bonnet. After the car has been sat, heat from the engine bay warms this area, it drops off fairly quickly once under way and is obviously accurate from a cold start.
Ideally i'd like a longer lead on both sensors, the internal one could go in a more "real world" place like behind the A-pillar trim and the external one could be sited either further forward just behind the radiator grille or in a wheelarch or similar. I'll look into a longer sensor for the external one then use the present external one as the internal one in a better place - all stuff for the future and if i take the positions of the current sensors into consideration and allow time for them to settle, i get sensible readings.

Ultimately i'll also fit some remote buttons for the setting of the clock but for now i'm happy that it's in there and providing some useful information!

https://www.ebay.co.uk/itm/Multifunc...1/392348762865

That's the new module, available in a choice of display colours (red, blue and green) from various sellers. Mine had to come from China on a slow boat so i've been waiting a while to fit it.

Hopefully that gives some insight into the dodgy fuel gauges and maybe other problems with the clusters! This one is a Yazaki so is likely to apply to most 940s/960s as well as facelift 7xx, the earlier VDO clusters have their own strange problems and because many of them were made before the EU Directive on solder, are less likely to suffer this particular problem.

TonyS9 · Nov 22nd, 2019, 13:47

I'm dissappointed you don't seem to support lead free solder. The techncial bodies throughly researched the alternatives and allowed manufacturers to state whether or not the replacements where effective or not. All presentations where considered before making the legislation to improve the risk of waste processor workers health. Also we are the EU and were instrumental in the proposing and uptake of such regulations, it would not have happened without the UKs agreement. May politicans blame 'the EU' for various things, but it isn't a seperate country, if the UK didn't want it it wouldn't happen.

Incidentally RoHS for most electronics didn't happen until 2006, so any RWD volvo's are gonna have leaded solder. Looks like there is alot of remaining flux on the joints that hasn't been cleaned off. I'd suggest that is more likely the problem than the type of solder.

Laird Scooby · Nov 22nd, 2019, 14:23

Forget RoHS Tony, this was way before then! It cost many firms (including the one i worked for at the time) an enormous amount to change over to lead-free solder. When the replacement stuff was new, sure, it performed like leaded solder.

However experience has taught me over the 30+ years in between that the lead-free solder DOES NOT stand the test of time.

There are countless examples of it and let's not forget here, many companies sprang up overnight prodcuing lead-free solder, each one cheaper than the last (bear in mind lead-free solder was initially a lot more expensive than leaded) so companies were switching from supplier to supplier faster than they changed their socks.

Unfortunately because it was pre-internet (1994) it's not well documented online and so far i've only found the 2003 RoHS Directive on lead-free solder. I did find a couple of references to it being compound fumes, rather than just the lead part of the fumes, i.e. the fumes from all of the solder were toxic, not just the lead part.

As for us not allowing the EU to pass Directives that would effect us, not correct at all. Just one example, some time in 1985 a UK law was passed stating that all new cars sold in the UK from 1/7/86 must have dim-dip lighting. Within 3-4 years (i'm not certain of the exact date) the EU had forced us to recind our own law and allow the sales of cars without dim-dip. At the time, Sweden wasn't in the EU yet they were still allowed to insist on Guiding Lights as a minimum (what we know as Day Running Lights) requirement for all new cars sold there. Go figure, as our American cousins say!
Any time we have tried to resist EU Directives, we have been threatened with sanctions if we don't comply.

This thread isn't about the EU though, it's about a fix for some common fuel gauge problems. It may not work for everyone, as we all know the gauges are prone to failure, again more often from the late 80s onwards - i really can't think why - or can i?

As for lead-free solder, it's responsible for many Mk3 Escort (and Escort based Orion) models fusebox failures, likewise with the Mk2 Rover 800 fuseboxes, many other related problems related to age/vibration etc due to the lead-free solder not being resilient enough.

TonyS9 · Nov 22nd, 2019, 15:13

I had to implement RoHS in 2006 from the 2003 directive working for a large electronics manufacturer. Prior to that there may have been lead free solder available. It is quite hard to tell the different without an XRF scanner. Contaimnated solder of any type certainly can go 'off'. and flexi PCBs are always troublesome. The 360 uses mainly crimp joints on its flexy, corrosiion leads to over heating.

Regulations are now my day job, I don't normally deal with the End of life vehicle regulation but it might go in place of ROHS and does predate it a little. Its a 2000 directive so probably won't have been a requirement until 2003 or so. Blaming 20yo electronics on lead free solder is flawed.

I don't want to get into a EU debate and don't know the dim dip story but I can assure you as a regulatory professional that the EU does not force us to do anything. We agree to regulations after a lengthy debate and discussion process from ALL stake holders and members of the public They are then implenented by all member states, if the UK doesn't agree it doesn't happen. When the politician that agreed to it realises that the result wasn't good for the UK or didn't take something into account they blame 'the EU'. Part of the problem is that these are technical regulations and the politicians have no clue whats going on.

tofufi · Nov 22nd, 2019, 15:56

Quote:

Originally Posted by TonyS9

.

I don't want to get into a EU debate and don't know the dim dip story but I can assure you as a regulatory professional that the EU does not force us to do anything. We agree to regulations after a lengthy debate and discussion process from ALL stake holders and members of the public They are then implenented by all member states, if the UK doesn't agree it doesn't happen. When the politician that agreed to it realises that the result wasn't good for the UK or didn't take something into account they blame 'the EU'. Part of the problem is that these are technical regulations and the politicians have no clue whats going on.

This!

Dave, I can find no evidence at all for your claim of a ban on leaded solder in the workplace in the 1980s. It was only in the 1980s that lead solder was banned from being used in drinking water applications...

I also work in legislation and can confirm that we don't have EU rules 'forced' upon us. The politicians make political decisions on what to accept, and have often blamed the EU whenever something unpopular is implemented...

tofufi · Nov 22nd, 2019, 16:11

Quote:

Originally Posted by Laird Scooby

.

As for us not allowing the EU to pass Directives that would effect us, not correct at all. Just one example, some time in 1985 a UK law was passed stating that all new cars sold in the UK from 1/7/86 must have dim-dip lighting. Within 3-4 years (i'm not certain of the exact date) the EU had forced us to recind our own law and allow the sales of cars without dim-dip. At the time, Sweden wasn't in the EU yet they were still allowed to insist on Guiding Lights as a minimum (what we know as Day Running Lights) requirement for all new cars sold there. Go figure, as our American cousins say!
Any time we have tried to resist EU Directives, we have been threatened with sanctions if we don't comply.

.

1) we would have been part of putting UNECE R48 into the European approval legislation. Whether parts of government were talking together enough to notice it'd be a problem is another matter...

2) Why on earth do you think the EU could make a non-EU country follow EU legislation that we formed?

Laird Scooby · Nov 22nd, 2019, 16:41

As i've already stated, this is about a fuel gauge fix NOT the EU but since you asked :

Environmental regulation and RoHS
Environmental legislation in many countries, and the whole of the European Community area (see RoHS), has led to a change in formulation of both solders and fluxes. Water-soluble non-rosin-based fluxes have been increasingly used since the 1980s so that soldered boards can be cleaned with water or water-based cleaners. This eliminates hazardous solvents from the production environment, and from factory effluents. Those regulations have also reduced the use of lead based solders, and caused the melting temperatures of solders in use to increase by up to 60 °C (100 °F).

That is an excerpt from :

https://en.wikipedia.org/wiki/Soldering

Just because you couldn't find it easily doesn't mean it didn't happen!

It pre-dated the RoHS legislation (which is EU based) by 20ish years and the instrument cluster in my car is 32 years old, not 20 years old. Back in the mid 90s, i was seeing problems with Escort/Orion fuseboxes and i have proof that the fusebox on my 1994 827 Sterling was renewed in 1999 under warranty because the solder joints had failed. None of these were even approaching 10 years old, never mind 20 years old and certainly not 32 years old!

360beast · Nov 22nd, 2019, 18:17

Just my 2p, I use solder daily and find it is absolute junk compared to the old lead solder my dad has in his garage. It takes forever to melt and always runs off the wiring I'm trying to solder.

bob12 · Nov 22nd, 2019, 19:00

Oh, ..... the aromatic vapours of 'Multicore' (trade mark) 5 core solder with resin just made you want to take a deep breath and lay back!

TonyS9 · Nov 23rd, 2019, 04:16

There were no regulations on work place soldering prior to RoHS, that would have affected my workplace too, we wouldn't have been allowed to use leaded solder prior to 2006 (which we did in consumer electronics). For fumes, we needed to have effective extraction for machines and hand soldering, we were tested on this regularily, it was mainly looking for flux components.

As to leaded and non-leaded performance, I have no trouble in using either. Yes the melting point can be different, but it depends on the exact formulation, you have to adjust your technique. Some high lead contents solders are actually very high melting point (there is a RoHS exemption for this, its needed for components that have soldering inside them).

Anyway the point of all this is to say a 700/900 series Volvo will be leaded solder.

Nov 22nd, 2019, 08:51	#1
Laird Scooby Premier Member Last Online: Yesterday 23:44 Join Date: May 2012 Location: Lakenheath	Fuel Gauge Fault - Fixed! Plus Ext. Temp/Time/Volts Display! We all know the fuel gauges on the 7/9xx are prone to not working or only working intermittently. Since i got my current 760, the gauge has had the work ethics of a 1970s coal miner. My previous 740 was the same and i designed and built an LED bargraph gauge for that : Having done various tests on my 760, i had come to the conclusion that wasn't an option. The fault appeared to lie somewhere between the gauge and the car wiring - that left the PCB on the back of the instrument cluster. Looking at that, at first glance it looks like an explosion in a spaghetti factory but delving in, i made some sense out of it. The 3-pole connector on the PCB centre-top is +ve, -ve and speedo signal. This also provides the +ve feed for the rest of the cluster including warning lamps, speedo and temp gauge. You'd think if the fuel gauge was dropping out, the rest would as well? In several cases you'd be right but have a look at these pics : This is a close up of 3 out of the 4 solder pad connections near the PCB fuse to the left. at the top. They weren't great and using the continuity tester on my multimeter, i could switch the buzzer in it on and off by wiggling the PCB around the fuse area. As such, these 4 pads were my first port of call for repair. Smeared a little soldering flux on them, heated them up with the iron and removed the old solder with a solder-sucker. A little more soldering flux then resoldered with some new real solder - that's most of the problem, the original isn't proper solder! Thanks to the EU, back in the mid-late 80s, leaded solder in the workplace was outlawed by the EU - the lead-free replacement does NOT stand the test of time! I also added an aftermarket clock/internal & external temperature display/voltmeter, picking up the +ve feed from the back of the fuel gauge and the -ve from the electronic rheostat for the panel lighting on the back of the cluster. I need to make a proper bracket for the display module and find better places for the temperature sensors (they can give some strange readings at present due to their locations! ) but here's the module fitted to the cluster : After repairing theose 4 solder pads, i was hopeful i'd cracked it, especially as i'd been able to make at least one of them act as a switch! However, testing in the car proved me wrong, although for the first 10 minutes i thought i'd done it. Then the fuel gauge dropped like a stone and the display disappeared from the module. This was incredibly useful in diagnostic terms. It left two more solder pad connections that were potentially the source of the fault. The one just underneath the indicator tell-tale and the one the other end of the dotted line from it. These two in fact : Left hand pad, near the tell-tale. 'orrible, ain't it? Pad t'other end of the dotted line, not much better! After removing old solder and applying new! Refitted the cluster yesterday morning and had to go shopping which gave it a reasonably long test - all good thankfully, despite doing everything i could to make it fault! I'd previously worked out that if the gauge worked from cold, once i got some warmth in the car, it would die. Conversely if it didn't work from cold, by getting some warmth into the car, i could make it work - turning the heat down after this would cause it to drop out again. None of these things effect it now thankfully! Also a short vid of the module in operation : https://youtu.be/qe5B09I4BYk One of the temperature sensors is tucked onto a clip on the back of the instrument cluster so gets all the heat from the footwell and any heat from the cluster, the other goes into the engine bay then onto the plenum cover over the wiper mech under the bonnet. After the car has been sat, heat from the engine bay warms this area, it drops off fairly quickly once under way and is obviously accurate from a cold start. Ideally i'd like a longer lead on both sensors, the internal one could go in a more "real world" place like behind the A-pillar trim and the external one could be sited either further forward just behind the radiator grille or in a wheelarch or similar. I'll look into a longer sensor for the external one then use the present external one as the internal one in a better place - all stuff for the future and if i take the positions of the current sensors into consideration and allow time for them to settle, i get sensible readings. Ultimately i'll also fit some remote buttons for the setting of the clock but for now i'm happy that it's in there and providing some useful information! https://www.ebay.co.uk/itm/Multifunc...1/392348762865 That's the new module, available in a choice of display colours (red, blue and green) from various sellers. Mine had to come from China on a slow boat so i've been waiting a while to fit it. Hopefully that gives some insight into the dodgy fuel gauges and maybe other problems with the clusters! This one is a Yazaki so is likely to apply to most 940s/960s as well as facelift 7xx, the earlier VDO clusters have their own strange problems and because many of them were made before the EU Directive on solder, are less likely to suffer this particular problem. __________________ Cheers Dave Next Door to Top-Gun with a Honda CR-V & S Type Jag Volvo gone but not forgotten........

Nov 22nd, 2019, 14:23	#3
Laird Scooby Premier Member Last Online: Yesterday 23:44 Join Date: May 2012 Location: Lakenheath	Forget RoHS Tony, this was way before then! It cost many firms (including the one i worked for at the time) an enormous amount to change over to lead-free solder. When the replacement stuff was new, sure, it performed like leaded solder. However experience has taught me over the 30+ years in between that the lead-free solder DOES NOT stand the test of time. There are countless examples of it and let's not forget here, many companies sprang up overnight prodcuing lead-free solder, each one cheaper than the last (bear in mind lead-free solder was initially a lot more expensive than leaded) so companies were switching from supplier to supplier faster than they changed their socks. Unfortunately because it was pre-internet (1994) it's not well documented online and so far i've only found the 2003 RoHS Directive on lead-free solder. I did find a couple of references to it being compound fumes, rather than just the lead part of the fumes, i.e. the fumes from all of the solder were toxic, not just the lead part. As for us not allowing the EU to pass Directives that would effect us, not correct at all. Just one example, some time in 1985 a UK law was passed stating that all new cars sold in the UK from 1/7/86 must have dim-dip lighting. Within 3-4 years (i'm not certain of the exact date) the EU had forced us to recind our own law and allow the sales of cars without dim-dip. At the time, Sweden wasn't in the EU yet they were still allowed to insist on Guiding Lights as a minimum (what we know as Day Running Lights) requirement for all new cars sold there. Go figure, as our American cousins say! Any time we have tried to resist EU Directives, we have been threatened with sanctions if we don't comply. This thread isn't about the EU though, it's about a fix for some common fuel gauge problems. It may not work for everyone, as we all know the gauges are prone to failure, again more often from the late 80s onwards - i really can't think why - or can i? As for lead-free solder, it's responsible for many Mk3 Escort (and Escort based Orion) models fusebox failures, likewise with the Mk2 Rover 800 fuseboxes, many other related problems related to age/vibration etc due to the lead-free solder not being resilient enough. __________________ Cheers Dave Next Door to Top-Gun with a Honda CR-V & S Type Jag Volvo gone but not forgotten........

Nov 22nd, 2019, 16:41	#7
Laird Scooby Premier Member Last Online: Yesterday 23:44 Join Date: May 2012 Location: Lakenheath	As i've already stated, this is about a fuel gauge fix NOT the EU but since you asked : Environmental regulation and RoHS Environmental legislation in many countries, and the whole of the European Community area (see RoHS), has led to a change in formulation of both solders and fluxes. Water-soluble non-rosin-based fluxes have been increasingly used since the 1980s so that soldered boards can be cleaned with water or water-based cleaners. This eliminates hazardous solvents from the production environment, and from factory effluents. Those regulations have also reduced the use of lead based solders, and caused the melting temperatures of solders in use to increase by up to 60 °C (100 °F). That is an excerpt from : https://en.wikipedia.org/wiki/Soldering Just because you couldn't find it easily doesn't mean it didn't happen! It pre-dated the RoHS legislation (which is EU based) by 20ish years and the instrument cluster in my car is 32 years old, not 20 years old. Back in the mid 90s, i was seeing problems with Escort/Orion fuseboxes and i have proof that the fusebox on my 1994 827 Sterling was renewed in 1999 under warranty because the solder joints had failed. None of these were even approaching 10 years old, never mind 20 years old and certainly not 32 years old! __________________ Cheers Dave Next Door to Top-Gun with a Honda CR-V & S Type Jag Volvo gone but not forgotten........

Nov 22nd, 2019, 13:47	#2
TonyS9 Premier Member Last Online: Apr 9th, 2024 21:44 Join Date: Jul 2009 Location: Holywood	I'm dissappointed you don't seem to support lead free solder. The techncial bodies throughly researched the alternatives and allowed manufacturers to state whether or not the replacements where effective or not. All presentations where considered before making the legislation to improve the risk of waste processor workers health. Also we are the EU and were instrumental in the proposing and uptake of such regulations, it would not have happened without the UKs agreement. May politicans blame 'the EU' for various things, but it isn't a seperate country, if the UK didn't want it it wouldn't happen. Incidentally RoHS for most electronics didn't happen until 2006, so any RWD volvo's are gonna have leaded solder. Looks like there is alot of remaining flux on the joints that hasn't been cleaned off. I'd suggest that is more likely the problem than the type of solder.

Nov 22nd, 2019, 15:13	#4
TonyS9 Premier Member Last Online: Apr 9th, 2024 21:44 Join Date: Jul 2009 Location: Holywood	I had to implement RoHS in 2006 from the 2003 directive working for a large electronics manufacturer. Prior to that there may have been lead free solder available. It is quite hard to tell the different without an XRF scanner. Contaimnated solder of any type certainly can go 'off'. and flexi PCBs are always troublesome. The 360 uses mainly crimp joints on its flexy, corrosiion leads to over heating. Regulations are now my day job, I don't normally deal with the End of life vehicle regulation but it might go in place of ROHS and does predate it a little. Its a 2000 directive so probably won't have been a requirement until 2003 or so. Blaming 20yo electronics on lead free solder is flawed. I don't want to get into a EU debate and don't know the dim dip story but I can assure you as a regulatory professional that the EU does not force us to do anything. We agree to regulations after a lengthy debate and discussion process from ALL stake holders and members of the public They are then implenented by all member states, if the UK doesn't agree it doesn't happen. When the politician that agreed to it realises that the result wasn't good for the UK or didn't take something into account they blame 'the EU'. Part of the problem is that these are technical regulations and the politicians have no clue whats going on.

Nov 22nd, 2019, 18:17	#8
360beast Go redblock or go home Last Online: Today 01:01 Join Date: Feb 2012 Location: UK	Just my 2p, I use solder daily and find it is absolute junk compared to the old lead solder my dad has in his garage. It takes forever to melt and always runs off the wiring I'm trying to solder.

Nov 22nd, 2019, 19:00	#9
bob12 bob12 Last Online: Yesterday 11:19 Join Date: Aug 2006 Location: Woking	Oh, ..... the aromatic vapours of 'Multicore' (trade mark) 5 core solder with resin just made you want to take a deep breath and lay back!

Nov 23rd, 2019, 04:16	#10
TonyS9 Premier Member Last Online: Apr 9th, 2024 21:44 Join Date: Jul 2009 Location: Holywood	There were no regulations on work place soldering prior to RoHS, that would have affected my workplace too, we wouldn't have been allowed to use leaded solder prior to 2006 (which we did in consumer electronics). For fumes, we needed to have effective extraction for machines and hand soldering, we were tested on this regularily, it was mainly looking for flux components. As to leaded and non-leaded performance, I have no trouble in using either. Yes the melting point can be different, but it depends on the exact formulation, you have to adjust your technique. Some high lead contents solders are actually very high melting point (there is a RoHS exemption for this, its needed for components that have soldering inside them). Anyway the point of all this is to say a 700/900 series Volvo will be leaded solder.

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