HI I have a 1994 volvo 940 turbo, my main problem is the speedometer and odometer stop working, and if I tap on the dash near the speedo it works again, But this is starting to be a pain in the knuckles as it can happen 1 or 8 times during a short trip any ideas Please, Thanks Phil

 

Obviously it's in the dash, i.e. th instrument pod. May be a loose connection if you are lucky. I'd take it out and make sure that all the connections are good-grounds, etc..

 

I have a 1990 740 base wagon speedometer was erratic for a time , from zero to 60 and would just stop all of a sudden. It would not work for awhile and then when I hit a bump in the road it would start working again. Then it would stop like it had a loose connection. Odometer does not work either, sometimes I would drive as many as 30 miles with it not working , then all of a sudden it would work for 3 miles or so and then stop. What would be causing this problem?

 

It is run off an electronic pick up in the rear end which may have gotten chafed or damaged but most likely it's the electronics in the speedometer itself, the capacitors. They need to be replaced--a fiddly piece of work which may or may not be successful in the end. You can try speedometer shops; new the speedos are very costly.

 

I have looked under the car and where the wire hooks up to the connector of the sensor some of the wires are broken . Is there a way to get the wiring for this without getting the sensor too? I think this is my problem.

 

I doubt that's still available, just get it spliced up! It's just wire...

 

I believe its a twisted pair. there's a plug at the sensor with two pins, brown and green-white, brown is the ground wire. that wire goes to a connector in the trunk, and upstream from that, its brown-white and green-white, where again brown-white is the ground wire.

 

Well, if you can hit the dash and get the speedo to change its ways, obviously the problem is in the dash, in addition to the wiring chafed in the back which is probably not a factor right now. Most likely the speedo capacitors are bad.

 

does this model have both a front and rear speedo sensor? I have seen this mentioned in manuals. does the connector supposed to have a tie of sorts holding it together?

 

front wheel sensors are for ABS. all models of 240/740/940 have the speedometer pickup in the differential (except early 240's with mechanical speedometers)

the speedo connector is a 3 pin thing that fits directly onto the back of the speedometer module within the instrument panel. it has + (power), speedo signal, and ground.

 

Is the speedometer pickup the same as the speedometer sensor? I noticed that if you pull it out of the differential , I would have to move a metal beam of some sort to be able to pull it out. If the wiring part comes separate , I would like to just replace it without having to take out the beam or loosen one side.

 

are the wires that go to the pickup or sensor two wires or a bunch of wire , I seen that the wires that are broken has a bunch of small wires . Is it possible to take two wires and connect each end to the connectors and make it work?

 

that 'beam' is the panhard rod...



As I said before, there should be a plug right at the sensor/sender/pickup (all names for same thing)... it has two pins, two wires, that form a 'twisted pair' (the ground and signal wire are twisted together, this improves noise immunity). If I'm remembering correctly, there's a couple feet of wire, then another connector somewhere in the truck area, then the wires that go up to the dash.

 

does the wire connector have to have a cable tie to hold it together with the sensor?

 

both mine do. i assume they are there to keep them from working loose, there's a lot of vibration on the rear axle when you're on a rough road at speed.

always use quality brand (G-B or equiv) BLACK UV protected tiewraps in automotive applications. the usual white ones will crumble in a couple years.

 

How hard would it be to loosen the bolt that holds the pan hard rod? In case I absolutely have to take it loose the remove the wire

 

wild guess says its on there with fairly high torque, so you'd better have a 1/2" drive 6-point socket, and a suitable torque wrench to replace it.

ah, service docs say 85 Nm (63 ft-lbs) for either end of the 700/900 live axle track rod (aka panhard rod). that not quite as high as I guessed it might be. some of the other rear end bits are 105 ft-lbs.

 

does one of the wires a shielded wire? and does the wire connector have a built in safety switch to keep the car from starting, I had it unhooked at the opposite end of the sensor and left it off for awhile and later I was trying to start the car and it would crank but would not start

 

I believe the speedometer wire is a unshielded twisted pair (ground twisted with signal), but its been so long since I've been in there I can't vouch for this.

it shouldn't prevent starting.

 

when I plugged it back in it started