1800E Electrical shenanigans.

[142 Guy]

I am smelling an ignition switch problem (amongst other problems).

I found a wiring diagram for a 1972 1800E and a 1973 1800ES. Both were similar so I am going to hope that this applies to your model.

There is a red wire from the alternator B+ terminal to terminal 30 on the ignition switch. This is the 12 v supply for everything that is switched in the car. In the run position it is connected to terminal 15 of the ignition switch which has a yellow wire. This wire is bussed across fuse 3, 4, 5, and 6 so it supplies anything connected to those fuses - including dash stuff supplied by fuse #4. The bussed supply side of the fuses also has a brown wire which goes to the ignition coil + and the D jet main relay. The brown wire is effectively connected directly to the yellow wire so it is unfused.

When you crank the starter motor, terminal 30 of the ignition switch is connected terminal 15 and to terminal 50 of the ignition switch which is a blue wire which goes to the solenoid on the starter. There are no fuses in this circuit.

If the starter motor works and the main connection from the battery to the starter motor is intact the starter motor will crank since there are no fuses in that circuit. So, fiddling with the fuses would not resolve your no crank problem. The engine should start even if every fuse is blown (with the exception of the fuel pump fuse). So, I don't think the fuses are the direct cause of the problem. I think your ignition switch is dodgy and may be operating intermittently. Check for connection between 30 and 15 in run position and 30 and 15 and 50 in the start position. It is possible that your short which blew fuse #4 advanced the deterioration of the ignition switch.

[swedishandgerman]

I've seen something similar on 140 Volvo. Check your alternator output. Or should I say, your voltage regulator output.

The voltage regulators on Volvos from that era give up resulting in far too high voltage, well in excess of 14v. The initial effect is that the gauges read very high; that's because the little volatge stabiliser for the dials reduces by about 40% IE: if the input voltage is 12- 14v, the output voltage is 5V whereas if the input voltage is say 15v +, the out put voltage is 6! Ends up wrecking the voltage stabiliser

[142 Guy]

Originally Posted by swedishandgerman

I've seen something similar on 140 Volvo. Check your alternator output. Or should I say, your voltage regulator output.

The voltage regulators on Volvos from that era give up resulting in far too high voltage, well in excess of 14v. The initial effect is that the gauges read very high; that's because the little volatge stabiliser for the dials reduces by about 40% IE: if the input voltage is 12- 14v, the output voltage is 5V whereas if the input voltage is say 15v +, the out put voltage is 6! Ends up wrecking the voltage stabiliser

Sleek lemur likely has multiple electrical 'issues', so it is entirely possible that the operating voltage of the alternator / regulator is out of spec. However, an out of spec charging system would not cause the no dash lights / inability to start the motor problem which sleek lemur recently reported. He needs to fix that problem first and get the engine running which would then allow a check of the running voltage of the charging system.

As an observation, I believe the stabilizer output voltage on the 1800 is around 10 volts as opposed to 5.1 volts on the 140. However, that may not make any difference in terms of what input voltage the stabilizer cooks itself (it is based on a thermal timer switch) . The 140 stabilizer probably reaches its upper switching limit above 15 volts and at that point the stabilizer output voltage goes up as the square of the input voltage. At that point your gauges will definitely start to read high and the stabilizer thermal timing element may cook itself.

[HRA]

I encountered a similarly odd problem with the electrics on my Amazon a few years ago. Probably not the same fault but...

I was on holiday driving down to Dover to catch the ferry. The car was going well on the motorway when suddenly overdrive disengaged. Quarter of a mile later the engine stopped. I put on the indicator to pull over onto the hard shoulder but that didn't work either. With a fixed ferry-booking I wasn't best pleased and didn't have time to call roadside assistance.

I hurriedly checked all the fuses but they looked fine. The contacts didn't look terrible either, but I rotated each fuse a few times just to give it a bit of a "clean". Hey presto, the indicator started flashing and everything was fine. I caught the ferry with time to spare and drove along the French and Belgian coast to visit a friend in Knokke Heist.

I reasoned that one of the fuses must have been making bad contact, hence the car come out of overdrive and the indicator didn't work. The engine stopped a little later because at the time I had an electric fuel-pump fitted. The delay was while the carburettor float-chamber ran dry.

I had no more problems until the same thing happened on the same motorway going in the opposite direction on my return home. The same cure fixed the problem and got the car going again. So, the following day I cleaned all the fuse-contacts to bright shiny metal. That was certain to fix it!

As the nights drew-in that autumn I was driving more at night and, in the dark, I started to notice that the charge (IGN) light on the dashboard would sometimes illuminate very dimly as I was driving along. It didn't happen every time, or even for a whole journey, but I didn't worry too much since the battery seemed strong enough when starting, and I'd checked that the alternator was charging it at just over 14V.

The stalling problem occurred again a few months later, and then again. Finally, whilst twiddling fuses I spotted the problem: it was the half-length 35A fuse. This is a small fat ceramic pill with a metal cap at each end. The fuse itself is a short metal strip running between the caps and soldered to both. Except in my case one of the solder-joints was dry so there was only intermittent contact. Turning the fuse in the holder was enough mechanical manipulation to remake the connection for the next few hundred miles until heat, vibration or both caused it to go open-circuit again.

I replaced the fuse and the dodgy one is now sitting in my desk drawer waiting for me to think of it when I next have the soldering-iron out.

[Ron Kwas]

HRA;

...all classic...from symptoms, to fix...but not a long-term fix, because the conical Fuse 1 contact area is still not protected with a gas-tight-joint. Symptoms will return (as a function of how close to the sea and salt air your car lives). I suggest you read about ACZP, then procure and use it on all fuses.

ACZP: https://www.sw-em.com/anti_corrosive_paste.htm
AMP Indicator full ON: https://www.sw-em.com/AMP_Indicator_ON.htm
Dimly glowing AMP Indicator: https://www.sw-em.com/gastight.htm

Cheers

[sleek lemur]

Thank you all for your suggestions.

The ignition switch did seem to me to be the likely source, as no functions were working and there was no IGN light. I was able to confirm 12v input to the switch, but now that 142Guv has given me the tests to do, I shall get out there and do it. I probably do have multiple issues, you're right.

HRA, your problem does seem to mirror mine. What car do you have ? I think my fusebox is different you yours as I don't think I have a half-length 35A fuse. Strange, though how yesterday when I opened the fusebox and disturbed the poorly located fuse 9, suddenly all systems were operations.

To confirm, VStab recently changed, but to little effect on temp gauge, though fuel gauge now healthy. Recently changed voltage regulator as well.

Ok, off to the garage now!

And thank you all again. I really appreciate the time you take to help me.

[Ron Kwas]

SL;

Indeed the 122 vs 1800 FBs are similar only in the fuse type, and correctly noted, your 1800 only has 5 X 25mm sized fuses (no 7 X 17mm shorty 25A), so the common failure mechanism you need to be on the lookout for (and prevent with ACZP) is the poor conical connection. It is less likely, but not impossible for other intermittencies to occur (like terminal looseness or crimp corrosion), but less of a chance of terminal corrosion because of the protected location in the pass compartment.

Good Hunting!

[sleek lemur]

All systems still working on the car, so tests are a challenge. Also, my car is a 1970 1800E, which has quite different wiring to the 1972. My wiring diagram is very poor quality, from the Brooklands Books manual. So what I have done is take readings from the terminals on the ign switch in order that when the problem returns, I can quickly assess whether it's there.

There is no price against the ign switch unit on Brookhouse website and Skandix says "discontinued". Have emailed Brookhouse for clarification.

Question: is it simply a matter of unscrewing the switch from the back of the lock mechanism? Is there anything to be gained from removing and cleaning?

One last thing: someone has taken a cable from the live terminal of the ign switch to the brake light switch at the pedal! Why would someone do this? I need a decent wiring diagram to be able to correct this howler.

This is character-building!

[142 Guy]

Originally Posted by sleek lemur

All systems still working on the car, so tests are a challenge. Also, my car is a 1970 1800E, which has quite different wiring to the 1972. My wiring diagram is very poor quality, from the Brooklands Books manual. So what I have done is take readings from the terminals on the ign switch in order that when the problem returns, I can quickly assess whether it's there.

There is no price against the ign switch unit on Brookhouse website and Skandix says "discontinued". Have emailed Brookhouse for clarification.

Question: is it simply a matter of unscrewing the switch from the back of the lock mechanism? Is there anything to be gained from removing and cleaning?

One last thing: someone has taken a cable from the live terminal of the ign switch to the brake light switch at the pedal! Why would someone do this? I need a decent wiring diagram to be able to correct this howler.

This is character-building!

You can find a copy of the provisional service manual for the 1800E which should apply to your car here:

http://volvo1800pictures.com/sweden/...in_page_en.php

It may have a better wiring diagram.

Does the 1970 1800 E have the locking steering column with the key cylinder in the column proper - key comes out 90deg to the column? If so, the switch is probably identical to the 140 switch and is out of production (I have a spare safely squirreled away for my 140). Short of finding a used one on E Bay or the like, rehabilitation by cleaning is your easiest option. There are other options; but, all more complicated electrically. If you search on this forum, there was a detailed post years ago where the poster dismantled and cleaned the switch.

If it is like the 140 switch, the switch is easily removed from the back of the lock mechanism. If you distrust your wiring diagram, use masking tape tags on the wires with the switch terminal numbers to make for drama free re-installation.

One last thing: someone has taken a cable from the live terminal of the ign switch to the brake light switch at the pedal!

Probably because there was a wiring failure someplace for the brake light supply and a previous owner did not want to engage in the effort to do a proper repair.

This is character-building!

You appear to be a glass half full person!

[c1800]

Lemur, I may have posted this previously, however I highly recommend one of these. I have one, its very easy to read and indispensable when working on my ‘71 E.

https://colorwiringdiagrams.com/prod...800e-1969-1972