My Speedometer and Odometer work sometimes, but mostly not. . Based on other posts it looks like the sender is the problem. I looked under the car the other day and I think I have located the sender. Is it bolted in the back center of the rear axle at the differential?is there any other access to the plug, like through the trunk?

Thanks,
Woody

Well here is how far I got with troubleshooting the no speedometer issue. After I posted yesterday I ran the car for a while and the speedometer worked. Just to be on the safe side I wiggled under the car and shook the wires at the generator (sender ) end. Yep, you guessed it! Speedometer quit and stayed dead.

So I put the car up on the ramps and pulled the sender loose after unplugging the leads from the sender.Couldn't get the sender loose completely because of the panhard rod across the differential Tried to clean the plug contacts with brake cleaner. Put it all back together. Still doesn't work@!!!!!!!!

So A couple of questions
1. What would I be looking for going up or back to the Speedometer Volts, Mvolts or something else on either the brown wire or the green and white wire. I am assuming that the Sender is a basic Hall effect device and we probably don't have a way to read it.

2.Does the sender harness plug wire plug into anything else before going into the dash?

3. Somebody (Paul) mentioned getting a new pigtail, is it available from Volvo or are we talking salvage yard?

I'd feel better being able to trace the circuits and having a couple of known clean connectors the next time I get under the car.

All this trauma so I can sell the Car!

1991 Volvo 740T 222000 miles, runs good. Just had new timing belt 50 miles or so!

Let's hear from you folks,

Thanks for all who have replied!

Woody

I wouldn't replace the connector unless you can see physical damage to the wires. I know at some point Volvo improved the way the wires are supported. I don't know if that was a production change for a certain year, but I know if you order the harness part number now it has some kind of bracket.

So, if the wires are intact, it sounds like you need a new sensor. The insulation will be worn a few inches from the connector if it is bad. Pull the sleeve around the wires up a bit and look in there. If the insulation around the wires is good, the harness is OK.
--
Paul NW Indiana '89 744 Turbo 145K/ '90 745 turbo 127K

It is probably the two wires on the connector harness that are bad. I found the broken wires above the connector and buttspliced the wires to new pigtails and a connector.

Check the wiring before you jump to the sensor.
--
Paul NW Indiana '89 744 Turbo 145K/ '90 745 turbo 127K

Only accessable from the underside

i THINK IT IS JUST CLOGGED W/ A BIT OF DIRT.CHANGE THE OIL IN THE AXLE&BLOW IT OUT.OR MAYBE THE NEG,GROUND IS THE PROBLEM W THE STARTING STOPPING OF THE NEEDLE?