740 - weird electrical issue.

[redtel35]

Hi all,

Thanks for the quick replies and it seems as though the switch is definitely the issue.

I've already got the instrument cluster out as I've got to replace a couple of gauges.

The lower panel is also off as I had to trace some ropey fog light wiring.

Thanks for the help!

[Laird Scooby]

Originally Posted by stegreg

when you have spent 35 years of your working career as an auto electrician, I guess yes, I have changed a few ignition switches, but tbh, not many on Volvo's, no wont mention any other brands on here, im not one to offend .

To be fair, you'd want your customers cars to be reliable wouldn't you? Your reputation would be worth more than what you might save one person by using a secondhand switch?

Granted Volvo starter switches (as Volvo call them) aren't as "fragile" shall we say as many others but my points are nonetheless valid.

The biggest problem with getting a secondhand one is getting the correct one.

Many breakers will ask you for your part number and then tell you they've got it and send it to you (i'm talking about ebay here) and you fit it only to discover it doesn't work and then find they've sent the wrong part through.

No, what they've done is send the one they had in the belief they're all the same. You're then no further forward, have spent money on a switch that has no hope of working even if it's electrically sound and are struggling to get your money back.

The next biggest problem is you have no idea of the history of the switch you get from a breaker or how long it's likely to last. Don't forget that for most people going anywhere near the elctrical system is a fate wrose than death - they don't want to do it twice!

It might be a nearly new switch because someone has had trouble a few months before the car is scrapped in which case you're lucky or it might be on a really low mileage car scrapped because the owner was too old/ill to continue driving and couldn't afford the repairs to keep it going but those low miles represent being started 4 times a day and driving half a mile each time.

It could also be a high mileage car because it's owned by an antique dealer in Dundee who runs down to Sothebys in London once a week to sell what he's bought in Scotland and get a much better price for it but the car only gets started a few times each week, when he leaves Dundee and London to go home and for fuel stops in between.

Yes, these are extremes but purely to illustrate they can and do exist so you can't be sure of any secondhand part.

[Laird Scooby]

Originally Posted by redtel35

Hi all,

Thanks for the quick replies and it seems as though the switch is definitely the issue.

I've already got the instrument cluster out as I've got to replace a couple of gauges.

The lower panel is also off as I had to trace some ropey fog light wiring.

Thanks for the help!

You should be able to see the switch fairly easily, if you take the two screws out you should be able to pull it out far enough to either take a photo of the part number or see it easily enough to write it down. THen you should be able to get one from Volvo.

Out of interest, if you turn the key back manually to position 2 after starting, is power restored to the circuits that are cut during starting?

Also which gauges are you renewing?

[bob12]

I have found that the electrical part of the switch gear is very robust. Bob

[redtel35]

I need to replace the fuel gauge and the coolant gauge. I have managed to source the correct VDO replacements. I also need to replace the cog on the speedo as that has several teeth missing and so odometer has stopped working.

[redtel35]

Yes - if I turn the key slightly back (has to hit the right spot though), the radio comes on and blower starts up again.

[Laird Scooby]

Originally Posted by redtel35

Yes - if I turn the key slightly back (has to hit the right spot though), the radio comes on and blower starts up again.

I wonder if the barrel has become sticky after many years of use and a bit of lube (WD40 or for preference, silicone spray lube) sprayed into the ignition lock barrely would sort the problem out for you. I had that on one of mine, can't remember which now but solved it with a little squirt and some use. Could be worth a try and save you £OUCH on a new switch!

[Ian21401]

Originally Posted by Laird Scooby

I wonder if the barrel has become sticky after many years of use and a bit of lube (WD40 or for preference, silicone spray lube) sprayed into the ignition lock barrely would sort the problem out for you. I had that on one of mine, can't remember which now but solved it with a little squirt and some use. Could be worth a try and save you £OUCH on a new switch!

Usually a good thing to try initially. Quicker, less hassle and cheaper.
My windscreen wiper switch is becoming a little temperamental in that very occasionally the wipers do not actually start until I switch to the faster speed then back. First step will be to check out the switch, clean and lubricate.

[bob12]

Originally Posted by redtel35

I need to replace the fuel gauge and the coolant gauge. I have managed to source the correct VDO replacements. I also need to replace the cog on the speedo as that has several teeth missing and so odometer has stopped working.

I assume you are aware of this VDO trip meter fix info on Dave Barton's website at:

https://www.240turbo.com/740-odometer-repair.html

In the UK you can buy the 25 toothed gear wheel on the internet from 'PartsMonster' for about £10.00. It is described as being for a 240 but it's the same thing you will want. In fact you get another gear but it's highly unlikely you will need that.


Bob

[redtel35]

Thanks Bob,

Ordered the cog from Parts Monster yesterday.