cluster issues- help!

[papag1234]

So I'm having two issues with my cluster. I assume both are wiring.

89 325is motometer

1) Speedo does not work half the time. I know this is a wiring issue because I can reach my hand from underneath and wiggle the wiring around and it comes back to life until the next hard bump. Does anyone know exactly which wire is causing this so I can fix it? It's extrememly annoying not knowing my speed and when using cruise control (trying not to speed after my last ticket :() because when speedo craps out the cruise deactivates and the car falls on it's face.

2) the light on the right side of the cluster is out. I swapped the bulbs around with the other side and still no light on the right side. Also since this light is out, the light for the info panel (mpg, range, etc) next to the radio is out. The info panel is illuminated until I turn on the headlights/interior lights. Maybe once every few months the light on the cluster turns on again and whenever it does- so does the info panel. I assume it's something related to wiring as well.

Any input will be appreciated.

[Thizzelle]

sounds like a grounding issue

[ELVA164]

For #1, the first thing I would check is the plug at the rear of the gauge. Pull the cluster out, make sure the plug seats well and isn't loose, then if you find something reinstall it and see if it works.

#2 is interesting. The light in the onboard computer should be on all the time when the key is in the "accessory" or "on" position. The bulb in the cluster should be separate from that, but again there may be a plug issue. The plug for the OBC is green, by the way. I had one of the bulbs in my cluster work intermittently and after swapping in a couple spares I had it stayed on. There may be something loose in the cluster itself; check inside the socket and make sure the pins look straight and unbroken.

Another thing is there must be something odd at the interior/headlight switch that causes the OBC light to go out. I do know that when you turn on the running lights or headlights, the dimmer is then able to affect the OBC light so there is supposed to be a connection there. You sure the dimmer isn't all the way down? Checking grounds would be a good idea.

[Gregs///M]

If your speedometer works intermittently in conjunction with that wiggling then I would assume you have cracked solder joints or broken traces on your cluster main circuit board. Other options would be insulation failure in the wiring harness or damaged connector pins or sockets.

With any cluster problems, always start by checking or replacing fuse 10, 12, and 21. All speedometer issues should at least check the condition of the connector at the rear differential.

In your case, since you can cause a fault condition local to the cluster, I would say a broken solder joint which can affect both the speedo and the illumination. Both the left and right side of the illumination circuit are in parallel with each other so if one works, and the other doesnt, and the bulb is good, it can only be broken solder joints (or damaged landing pads for bulb sockets) or cracked electrical trace.

[papag1234]

Maybe it is a grounding issue. Are there any diagrams for the wiring to the cluster?

elva164 - #2 is interesting indeed. I've taken the plugs and and reseated them to no avail. Even if it was a bulb I still don't understand why the OBC blacks out when the right side of the cluster is not lit up.

The dimmer is turned all the way up... I probably try this every other day.

[papag1234]

If your speedometer works intermittently in conjunction with that wiggling then I would assume you have cracked solder joints or broken traces on your cluster main circuit board. Other options would be insulation failure in the wiring harness or damaged connector pins or sockets.

Concerning the speedo, I'm 100% sure it's the wiring to the plug/cluster that's no good. Just before I go in and cut every wire and rerun them all I would like to know if anyone has a pinout diagram for the cluster.

With any cluster problems, always start by checking or replacing fuse 10, 12, and 21. All speedometer issues should at least check the condition of the connector at the rear differential.

Checked all fuses already and the first thing I did when this problem arose was I took out that plug on the diff and cleaned it up with some anti-static electronic cleaner. No dice.

In your case, since you can cause a fault condition local to the cluster, I would say a broken solder joint which can affect both the speedo and the illumination. Both the left and right side of the illumination circuit are in parallel with each other so if one works, and the other doesnt, and the bulb is good, it can only be broken solder joints (or damaged landing pads for bulb sockets) or cracked electrical trace.

I understand what you're saying here- can any of these possible issues cause the OBC to fail also? Because like I said, these two events occur in conjunction. If the right side of the cluster is out- then the OBC is out. If the right side of the cluster is lit up- then the OBC is lit up. It lit up last night actually and a few nights before that. Before this week it's been months since they have last turned on. It's like a miracle when it lights up.

[Gregs///M]

Concerning the speedo, I'm 100% sure it's the wiring to the plug/cluster that's no good. Just before I go in and cut every wire and rerun them all I would like to know if anyone has a pinout diagram for the cluster.



Checked all fuses already and the first thing I did when this problem arose was I took out that plug on the diff and cleaned it up with some anti-static electronic cleaner. No dice.



I understand what you're saying here- can any of these possible issues cause the OBC to fail also? Because like I said, these two events occur in conjunction. If the right side of the cluster is out- then the OBC is out. If the right side of the cluster is lit up- then the OBC is lit up. It lit up last night actually and a few nights before that. Before this week it's been months since they have last turned on. It's like a miracle when it lights up.

I am fairly certain your problem is not the ground. If the cluster grounds were compromised, you would see intermittent or failed operation of all gauges at the same time. Not just only the speedo and one side of the illumination.

Yes the OBC illumination, as well as other power and signals, are routed between the cluster and the OBC, specifically the SI board. It does not surprise me that your OBC is failing at the same time as the cluster.

The way I would find the problem would be as follows:

1. Verify speed signal by probing the brown/red wire in the white connector at the cluster. With the vehicle raised, the signal from the wire should be pulsed and increase in freq as the wheels spin faster. This test will narrow down if the problem is located in the cluster or in the vehicle.

2. With the cluster open, you will need to trace each side of the cluster illumination socket and test for continuity between the positive socket pad and the source of the electrical trace where it meets the connector. Do the same for the negative side of the socket. You can repeat this test for the other socket, which should show continuity to its two sources. Basically you are testing the integrity of the printed circuit board electrical traces for the illumination circuit. If you find one "open" it will need to be repaired or whole PCB replaced.

Your other option is to send it to me. I can test it on my work bench and tell you everything wrong with it.