Another Dead Tach and Econometer

[ClayW]

Help me figure out what I did wrong (yes, I searched and I'm still stumped).

I have a VDO cluster.

A few weeks ago, I removed my cluster and soldered up the grounding post connections on the board to fix a bouncy temp gauge and a lying fuel gauge. After reinstallation, the fuel gauge was fixed , but the temp gauge was still kind of bouncy and the tach and econometer were dead.

I ordered new SI board batteries and soldered them into place on a a spare Motometer SI board. I installed it with zero change. So, I removed the SI board and desoldered the batteries from it. I then soldered the batteries into the VDO SI board and installed it. No change.

I checked, pulled and cleaned the fuses. Nothing.

I tried the stomp test and nothing happened.

What else should I look for?

EDIT: I read some more. I am going to check the solder joints at the tach connections for cracks.

[Gregs///M]

First start with your fuses. I know you check them but did you properly check them? Fuses should be check with a test light to ensure proper current flows through them. Some damaged fuses will show continuity with a digital meter but show open with a test light. If you are in doubt, just replace them.

SI board handles power and signal for the tach, MPG, and temp gauges. Are you sure you installed those batteries with the correct polarity? SI boards often develop damaged from screwing the cluster trim too tightly...

http://www.r3vlimited.com/board/showthread.php?t=274422

Other culprits could be solder joint cracks in the cluster main board or broken traces in the main board. Broken traces, although more rare, do occur. They are impossible to find even with a magnification. You must pin-check the associated electrical traces on the board.

Worse comes to worse, you can replace your cluster or send to me for rebuild. GL

[bubbajan21]

Greg, I have somewhat the opposite question. My temp, speedo, and mpg gauges work fine but the left half of my cluster is completely non-functioning. The speedo and fuel gauge don't work at all along with the lighting in that half of the cluster. Any thoughts?

[Gregs///M]

Greg, I have somewhat the opposite question. My temp, speedo, and mpg gauges work fine but the left half of my cluster is completely non-functioning. The speedo and fuel gauge don't work at all along with the lighting in that half of the cluster. Any thoughts?

I believe it to be coincidence that half the cluster works. For illumination, go ahead and replace the large light bulb that illuminates that side of the cluster. I would replace both or you will have one old and one new bulb, this different brightnesses.

The gas gauge is directly connected to the sensors in the fuel tank. Speedo is directly connected to the sensor in the rear differential. The only common item with these is the cluster main circuit board which can develop cracks in the solder joints and will need to be reflown with solder. Broken electrical traces can also occur which will require you to pin check all associated traces with a meter to verify they have continuity.

For you, first verify your speedo connector is free of corrosion and secure. Also tighten the 7mm nut behind the fuel gauge. start there.

[Killacortes]

When my eco gauge and my tach stopped working. I put a different coding plug in and that fixed the problem.

[bubbajan21]

I believe it to be coincidence that half the cluster works. For illumination, go ahead and replace the large light bulb that illuminates that side of the cluster. I would replace both or you will have one old and one new bulb, this different brightnesses.

The gas gauge is directly connected to the sensors in the fuel tank. Speedo is directly connected to the sensor in the rear differential. The only common item with these is the cluster main circuit board which can develop cracks in the solder joints and will need to be reflown with solder. Broken electrical traces can also occur which will require you to pin check all associated traces with a meter to verify they have continuity.

For you, first verify your speedo connector is free of corrosion and secure. Also tighten the 7mm nut behind the fuel gauge. start there.

Perfect, I will start with that, although I guess I forgot to leave out a very important detail. I'm pretty sure everything used to work (The car has been off the road for a year since the day I bought it with a motor swap, repaint, suspension, etc.) but when I installed the euro clock I forgot to disconnect the battery and shorted 2 wires. It blew a fuse and I replaced it and the clock works great but now the illumination on that half and the speedo and tach don't work. Again, they might not be related as I'm not positive that they worked in the first place, but I will start with what you recommended and report back.

[Gregs///M]

Perfect, I will start with that, although I guess I forgot to leave out a very important detail. I'm pretty sure everything used to work (The car has been off the road for a year since the day I bought it with a motor swap, repaint, suspension, etc.) but when I installed the euro clock I forgot to disconnect the battery and shorted 2 wires. It blew a fuse and I replaced it and the clock works great but now the illumination on that half and the speedo and tach don't work. Again, they might not be related as I'm not positive that they worked in the first place, but I will start with what you recommended and report back.

The illumination for the cluster is on the same circuit. So if one side works, and the other does not. It can only be a dead bulb or damaged electrical trace (or solder joint.) If both bulbs do not work, and there is no power, it is most likely vehicle wiring.

[ClayW]

It turns out that the problem was a fried trace on the cluster board. I checked the SI board anyway, but bridging this circuit was the solution.



Thanks for the help!