I was putting the belly pan on today, and while under there I decided to clean the ground cable on the underneath passenger side of the engine. Took it out for a drive afterward and initially everything was fine.

A few minutes into the drive, I lost the speedometer, tachometer, and fuel gauge. Oil pressure, water temperature, voltmeter, and the digital dash (including most importantly the odometer) all continued working.

I cleaned the ground by initally wiping off the dirt and grime, then used sandpaper to rough up both pieces and bolted it back up. Any idea what I did wrong and how to fix this? Thanks in advance.

 

fuse 25 or 26 IIRC

 

OK, I'll check that and report back. Thanks.

 

Nice 928, was the battery disconnected when you did this?

 

Reporting back:

Instruments, as it turns out, are on fuse 39 (correction: 25). I pulled it and the wire looked fine. However, the contacts were dark gray. I roughed them up with fine sandpaper, wiped them off and re-installed. Fired it up and had nothing for 5-10 seconds, and then they all popped back on.

Still don't understand how cleaning the ground would mess this up, but hey, it's working again so I'm happy. Looks like I have another project - cleaning all the contacts.

Thanks Roger!

 

Thanks Mark.

No, the battery was not disconnected. Was this my mistake?

 

Jarrod,
You may want to check all the fuses.
Bend the pins a little - one one way and the other the other way and then push them in and out of the holders a few times.
New fuses may be a good move.
Roger

Any more problems and I will take it off your hands for a small consideration 8>)

 

I'll either clean or replace all the fuses in the next few days. Despite the frustration, I think I'll keep her a little longer...

 

John Muir once commented on this: When I first read that, many years ago, I didn't realize that he was talking about 928's. In fact I didn't even know that he had one. But he must have, how else would he have learned such fundamental truths about the universe?

 

And, as Herman Munster once sung, the "anklebone's connected to the neckbone". Once again, referring to the Universe that contains the 928.

On our 86, evey time we started to jack it up, the hatch motor would run.

 

OK, if we want to discuss anomolies of the 928 universe, here's one from my previous '90GT:

For no apparent reason, the tuning on the stock Blaupunkt Reno 2 radio became off by 1.1 mhz (IIRC). I.E. to tune in 98.9 FM, you had to set it to 97.8. It remained like this for the duration of my ownership. Haven't figured that one out either.

 

I don't know if disconnecting the battery was your problem but (don't you love that word in any conversation) I always unhook the battery when ever I work on the electrical system. I wrote a couple of posts about my electrical system which has taken me over a year to figure out. Your D90 wheels rock!! And the color is awsome. If you ever think about selling your car email me! Mark

 

He has the best color, agreed.

Regarding the gauges, much trouble (but not all) seems to go away if the CE panel is pulled and all terminals are cleaned til bright. Then the pod connectors. And the speedo connector in the trunk area. So, for me, its not just the grounds.

 

try cleaning the fuse ends with a ink or pink eraser, they sould come clean. otherwise replacing all of the fuses is a great idea . Disconnect the battery first while working on the elex system

 

Fast forward to this evening - fuel, speedometer, and tachometer have continued to quit at times, while all other analog instruments and the digital portion continued to function normally.

The cause to date appears to have been voltage related. At the OCIC, when there was some battery drain with the doors open, the above instruments wouldn't work on departure. They came back on during the return trip to Tulsa. This is consistent with previous occurences. The car hasn't been driven much in the past month, and I took it out last night. Same deal, they quit again but this time did not come back on.

Soooo, tonight I unhooked the battery, pulled all the fuses, and sprayed the panel with electrical contact cleaner. After allowing to dry, I put the fuses back in and hooked the battery back up. The fuses were all recently replaced, btw.

Now, the same instruments still don't work and the digital portion, which WAS working, is simply FLASHING SOLID at me! Argghh, what have I done!?

Everything else electrical continues to work as it should. Anyone have any insight? I'm really steamed right now.