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1990 740 speedo problem

Hello again,

been a while since my last posting but have been keeping up with everything (pretty much anyway).

I've got a issue with my 1990 740's speedo. When traveling along at any speed over any surface it will just drop to zero. A well placed tap on the top of the dash brings the speedo back to life.

Some days it won't do it at all, others it won't work for miles and then bring itself back to life. I've had a feel around behind the speed (it's quite easy to access from underneath the dash) and can't feel anything that's come loose at all so I'm guessing that it's a dry joint somewhere.

Any suggestions as to what I should do? If possible, I'd like to avoid taking the dash apart but if needs must then so be it.

Thanks and regards,

Richard

Reply to
Richard Setford
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Solder joints on the instrument cluster PC board are the usual culprits.

Unless yours is very different from our 85 model (I don't think it is) getting the instrument cluster out and back in is very easy. Once the screws are removed from the front the cluster can be pulled far enough out to unfasten the connectors and voila! you have it. The connectors are unique, so there is no need to mark which goes where. Just note any connectors that are vacant on the cluster, and maybe tie a string to the connectors before you remove them so they don't try to lose themselves behind the dash (not really a problem). The cluster goes back in the reverse of the way it came out; slide the top in first.

Mike

Reply to
Michael Pardee

Yes- easy to remove. Also, I found that my octal connectors(?) were pretty dirty and needed cleaning as well. Also a good time to replace bulbs where necessary (look for darkened bulbs, and removing and replacing them also helps maintain a good connection. And i took the opportunity to remove the instruments and clean out the inside of the cluster as well.

__ __ Randy & \ \/ /alerie's \__/olvos '90 245 Estate - '93 965 Estate "Shelby" & "Kate"

Reply to
Randy G.

Doesn't the '90 use the newer instrument panel like the 940s have? I think it's a little different to remove, but still quite easy.

Reply to
James Sweet

Very easy (from memory):

-have container handy to hold hardware as it is removed.

-Disconnect battery

-Pry out horizontal trim strip below headlight switch panel (it pulls out back towards the driver)

-Remove the headlight and dimmer knobs (pull off)

-Pry out panel that holds rear fog light switch

-Pry out two dummy instrument covers (or instrument bezels if so installed) to the right of the instrument panel (between instruments and radio area).

-Remove 4 screws- two along the left edge and two on the right edge) of the instrument panel.

-Remove the metal shaft locator for the light switches.

-Center steering wheel and pull entire cluster out.

-Disconnect wires from back of cluster and remove cluster from car.

__ __ Randy & \ \/ /alerie's \__/olvos '90 245 Estate - '93 965 Estate "Shelby" & "Kate"

Reply to
Randy G.

The problem is that 740s continued to use the old VDO instrumentation as well as the Yazaki setup, whereas the 760s got the all-Yazaki instrumentation. I have a guy (UK) with just such a problem with a customer's 1990 740, where the instrument circuitry is quite different from the Yazaki layout. His problem seems to be the regulator has burnt out causing fuel and temp gauge problems and his VDO speedo became intermittent and has now stopped reading Trip and Odometer. This has a similar origin to the Yazaki instrument in that a small nylon drive gear wheel splits and no longer makes a good tight fit on the shaft.

All the best, Peter.

Reply to
Peter K L Milnes

More often than not the speedo is losing signal from the sensor in the diff. The wiring is not very stout and tends to break inside the insulation, due to excessive clamp force on the wire when the waterproof sleeves were molded over the connector.

Before you remove the wire seal on the sensor pull on the wires and see if they stretch easily. If they do you will have to replace the two wires in the connector with Volvo p/n 3523813. These are the wires for converting the early style 240 washer pump harness to the later connector on the pump motor. The wires in the harness are a twisted pair so take care to maintain the twist when splicing in the new wires.

Bob

Reply to
User

Thanks for all the suggestions guys, A job for next weekend me thinks.

I'll let you know how I get on.

Richard

User wrote:

Reply to
Richard Setford

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