740 Speedo Problem

Speedometer does NOT work. Does anyone know where I can begin to look for my speedometer problem? Are there any "recurring" problems with these things? TIA

Reply to
moster
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What year car?

Couple questions - do the odometer and/or trip meter work?

I have a 1987 740 - everything on the dash works except the speedo. Here's the most common problem: Jack up the rear of your car and look at the rear differential. There will be 2 wires with a snap on connector. There is a magnet inside of the diff that sends a signal through these wires to your speedo on the dash. If everything on the dash is dead - tach, speedo, mileage, chances are these wires have worn out, maybe shorting, etc. Often a repair of these wires will get you back in business. Unsnap the connectors and inspect. No need to take out the diff unit - VERY rare to fail.

If everything on the dash is working BUT the speedo - that's another issue. I just took apart my cluster and it was not fun - tons of little screws and when I pulled the speedo apart - coils of wires inside. From here you have two choices - replacement speedo from the boneyard or ship it off and pay the $100 or so they want.

Option three is find someone with instructions on repair. All I could find was for a 200 dash and the speedo is different I think.

jamie

Reply to
Jamie

Reply to
moster

You have two separate faults.

The odometer is as broken as they all are. The tiny plastic drive gear inside the odometer is stripped. There's a guy somewhere on the web who was selling spare gears, otherwise it's a squillion bucks for a new speedo from Volvo. Or else just live with it, like the rest of us. You can't get a scrapyard one because that will have the same fault too.

The intermittently dying electrical gauge (any gauge, take your pick) is caused by bad contacts through the dashboard plugs. Strip, clean, re-assemble. They all do that too.

It's unlikely to be the back end. If that fails then it's permanent rather than intermittent (rare, but it happens, and its usually just the wiring not the sender).

Reply to
Andy Dingley

Mine has never broken (knock on wood) and I've picked up several good spares from scrapyards. Perhaps climate has an effect on this? I just don't see many broken odometers in 740s.

Reply to
James Sweet

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