E30 speedo totally dead !

[jutilaje]

I KNOW this has been covered before, and I've spent the past few weeks searching threads, etc but haven't found anything specific to my problem. So, I have an 87 e30. Since I bought it, the speedo and odo (of course) have not worked. However, every other gauge (including the econometer) works flawlessly. I know the econometer is dependant upon the speedo and tach, so obviously it's getting speed signal from SOMEWHERE (it doesn't do the either 40mpg or 0mpg jump like others experience. It accurately sweeps up/down like it should). But, even with all that info, I went ahead and reflowed the solder on the back of the speedo. Still nada. I looked and of course the odo gears are trashed, but I don't think that has anything to do with speedo movement, right ? The gauge doesn't jump when I hit bumps, just stays dead all the time. When I removed the gauges I used my finger to sweep the needles and the speedo feels the same in terms of resistance as all of the rest of the gauges. Dunno if this means the stepper motor is good or not. Lol. Any ideas what else it might be ? I DID notice under the hood there is a yellow 2-wire plug on the driver's side just in front of the strut tower (think that's what it's called?) that has been cut (more like chewed through). When I traced it, one end goes to the fusebox harness and the other goes down into the wheel well and connects to the hub. Is this the wheel speed sensor for ABS? Would that affect the speedo? Thanks in advance for any help!

[jlevie]

The odomoter and speedometer are independent functions within the speedometer. In this case I'd say that you need to replace the speedometer. The speed signal for the speedometer is from the sensor in the differential. If the econometer, SI indicators, and on cars with the 13 button OBC the speed/range functions work the speed signal is present at the cluster.

[Gregs///M]

Speedo and odometer rely on three main power sources. Power, Ground, and Signal.

I would first start by replacing fuse 10, 12, and 21 in the fuse box with 7.5A. Then check the condition of the conductors in the speed sensor connector at the rear differential. Also check that there is no wire breaks.

At the white harness connector behind the gauge there is a brown and brown/red wire. The brown wire should show continuity with ground at all times. The brown/red wire will show a pulsed signal that increases with wheel speed. You can measure it with a test light or meter set to continuity or ac volts.

If signal is present and power is present, either the solder joints on the main cluster board are bad or on the speedo circuit board. Lastly, if that all checks out, there could be other electrical component failures on the speedo circuit board.

[Quinthirty]

What is the cause if the tach goes to zero while engine is running?

[Gregs///M]

What is the cause if the tach goes to zero while engine is running?

Bad/dead SI board batteries, impulse sensor wire break, DME failure, broken wire connection between DME and cluster, poor/broken solder joint in cluster main board to name a few.

[2mAn]

Bumping this back up since its a similar issue.

I had a long road trip this weekend (350miles) all gauges worked just fine, the next morning, no speedo and no odometer. Everything else works. Checked the fuses and all were good.

Gregs///M has already rebuilt this cluster and he replaced the SI batteries, and verified everything else, so Im not sure where to check.

Im kinda suspicious about this lone wire that comes out of the white plug.

Its been plugged and unplugged so many times, but recently I plugged it in again (just prior to the road trip). It didnt fix the issue I was working on (VSS signal to DME), but I did notice that when I would flash the highbeams the radio would make a quick popping sound. Im pretty sure there is a ground issue somewhere on this car, because my stereo also has this feedback noise that Ive been annoyed with for years


So is either related to this wire or maybe the Sensor in the diff??

[Todd Black 88]

Are all diff sensors the same for medium case duffs, or are they ratio specific?

[2mAn]

Are all diff sensors the same for medium case duffs, or are they ratio specific?

Never heard that there were different ones

[Gregs///M]

The rear differential speed sender is a very prone to brittle cracked wires and corrosion on the connector copper. this applies to all vintage BMW.

The speedo circuit is very simple.

The unit gets power, ground, and signal from the diff sensor. Since your fuses are good, your grounds are good (if cluster ground was bad, no gauges would work, cluster would go crazy) then it is most likely your rear speed sender.

Inspect the local wiring to the sender and the copper connector. Clean with a small fire or wire brush.

Also old fuses can sometimes "look" good even though they are bad. I suggest replacing, not checking the fuses, good luck.

[2mAn]

Thanks Greg! I will have some time this weekend to do it, and will report back

edit: it started working today :rofl: I will still look at whats going on at the diff

[SDbboy]

Thanks Greg! I will have some time this weekend to do it, and will report back

edit: it started working today :rofl: I will still look at whats going on at the diff

Did you ever figure out what the culprit was?

[l0gistaja]

Just got a similar issue. My car hadn't been started for like 2 weeks and now the instrument cluster is almost completely dead. The only things that work are the temperature gauge (starts working when I tap it with my finger) and the headlight indicator. Everything else is completely gone. Any ideas?

[dvallis]

Bump for an old thread. Has anyone found the right MPN on RealOEM for the speed sensor plug? Not the one in the diff, but the one that plugs into it?

[Striker01]

Bump for an old thread. Has anyone found the right MPN on RealOEM for the speed sensor plug? Not the one in the diff, but the one that plugs into it?

Sorry to bump an old thread but I just had a hard time finding this part number as well and want to add part numbers for future searches. If you can't figure out a part number just email Steve @ Blunttech, he got these for me. If you're not getting your parts from him, then you need to start. Exceptional service and quick to follow up on any questions.

Speed sensor connector: 61131378416 (only the housing that the 2 pin assemblies clip into)

The pins for it are pre-molded with pigtails. This is the part number for them: 61130007446

[slum dog]

My speedometer only works on rainy days or if I drive on a puddle of water it comes back to life.
Other than that no luck, swapped every part related with know working stuff, wiring seems fine cause it has resistance across.
I am gona try these pigtails.