Speedometer doesn't work! D:

[TimbyMaTombo]

I need help diagnosing my speedometer issue. My speedometer, odometer, trip, and MPG gauge all don't work. I assumed (hoped) it was the sensor on the differential that needed replacing. I replaced it with a new one and it still doesn't work.... What else should I check? The mechanic at Cars & Concepts in Tampa said it is probably the SI board, but I was wondering what you guys have to say about it.
Thanks
Peter

[jrobie79]

check your fuses...i went through the hassle of changing SI board batteries (probably good preventative maintenance anyways) and it turned out to be some beat fuses from shorting stuff out when removing my cluster to paint the needles.

[Gregs///M]

Check the wiring at the diff sensor. Since you have a new sensor, the connector itself could have corrosion or oxidation on it. Clean it up real good by what ever means necessary. Make sure the wire and connectors is secure and in good condition.

I suspect the cluster is not receiving speed signal at all.

This can be verified by jacking the car up and removing the cluster. Probe the brown/red wire on the white connector behind cluster. With a multimeter, you should read 1.5-6v AC while the rear wheels are spinning. Be sure you meter is set to AC volts. Or with a power probe (not test light), you should see pulsing signal to cluster.

If you don't see this pulsing signal (with wheels spinning) then the problem is the wires or sensor itself.

[dogsbark26]

I suggest your best bet at repair is to switch the speedometer head with a known good one. If you haven't been screwing with the rear axle or differential, the sensor and wiring rarely fail. Frequently though, the solder connections on the circuit board on the back of the speedometer fails resulting in intermittent operation.

[Gregs///M]

I suggest your best bet at repair is to switch the speedometer head with a known good one. If you haven't been screwing with the rear axle or differential, the sensor and wiring rarely fail. Frequently though, the solder connections on the circuit board on the back of the speedometer fails resulting in intermittent operation.

I do not suggest going down this road yet. Solder joint failure on the cluster main board is much more common, especially on the junction where the wiring harness is plugged in. The speedo and tach gauge solder joints are much more robust and rarely fail.

Re-flowing these components with new solder would be a much better and cheaper option. Only after verifying the speed signal is in the wiring harness.

[TimbyMaTombo]

Is the white connector you're talking about the white one to the left of the speedometer? There's a bundle of wires going into it and I don't know how I'm supposed to know which spot it is wired to...

[Gregs///M]

There are only three connectors.

Blue, yellow, white.

[TimbyMaTombo]

OKay, yeah that was a dumb question... I currently have the cluster out and I'm looking at it. Do I pull the brown/red wire out of the connector or should I cut it and reconnect it?

[Gregs///M]

probe it with sharp needle or strip a small length. Dont pull sockets out of connector.

[TimbyMaTombo]

Okay thank you. I'll do that.

[TimbyMaTombo]

Well, there was no current through the line... so I guess the problem is somewhere in the chassis wiring... ;-;