Eletrical grounds?

[aldersonr]

I'm restoring a 260Z that my parents have had sitting in the garage for over 12 years. So far I have replaced the brake system and am rebuilding the carbureutors since one was seized, but I'm having trouble with the dash instrumentation. According to the wiring schematic I have they share the same ground so I was wondering if anyone knew where the ground locations were? My dad drove it through a "puddle" that submerged it up to the bottom of the windows so I'm hopeing this is the problem. Also any other suggestions are welcome, thanks.

[aldersonr]

I would really like to get help with this if possible. It would mean alot to my mom to get her car running again. I am a recent Wyotech grad and would love to give her this as a thanks for everything she's done for me. Once again thanks for any and all help you could offer.

[MikeW]

If I'm not mistaken all of the instruments are simply grounded to the dash frame itself which is metal. Perhaps you can verify with an ohm meter that there's no resistance between the dash frame and another known ground on the body.

[aldersonr]

Thank you I will try that. You wouldn't happen to know where the ground may be located would you? Electrical gremlins are a pain to track down!

[MikeW]

I'm not sure I understand the question. There is a cable that goes from the negative side of the battery to the starter housing which is bolted to the bell-housing of the transmission at the rear of the engine. The entire body of the car is effectively grounded by this. The dashboard is attached to the car using quite a few bolts - any one of which would be sufficient to provide a ground for the dash. There's not a single point of failure if that's what you're looking for.

How did you decide that you've got a problem with the electrical ground? Do you have power to the fusebox? Does anything electrical work on the car?

[LB260Z]

I would split the wire harnesses open and inspect for corrosion and damage from the water. I did this on mine and solved all my "gremlins" be sure to label every plug you disconnect either as you go or ahead of time while things are still connected. look for bad connections(corroded) chances are though that after the whole mess getting soaking wet and sitting for several years, you may end up having to start over completely with new wiring for most of the car....

[aldersonr]

LB260Z- I was afraid of that but only as a last resort for now since the budget is limited and I don't think it was completely soaked. According to my dad he drove completely through the puddle and when he hit the top of the hill it stalled but started right back up and they drove it a little after that but only as a backup.

MikeW- I was hoping it was just a single point ground for the dash panel since that's what the diagram shows... As for power there seems to be constant through the fuse box. The main concern is that the insruments seems to take on different instruments. The tach acts like a voltmeter, the ammeter barely moves outside of starting, the fuel gauge doesn't work at all, and neither does the clock as far as I know. As for the speedo, oil pressure, and temp gauges I don't know either but everything else electrical works so really I'm just trying to narrow it all down. Thanks to both for the help!

[LB260Z]

honestly it does not really cost much to repair a harness and to properly start the diagnosis process correctly you should be starting with that in my opinion. much less guesswork in the end. you can test each wire at the terminals and determine the faults in the system, as well as visually inspect for corrosion or weak connections. if there was any water in its history, you can bet that something is surely corroded somewhere. when I did mine, I was very suprised at how much damage just a little water can do to old wires that "seemed" watertight. happy hunting!

[aldersonr]

That's probably what I'll end up doing. I was taught to do things right the first time, it just seems like a daunting tasks. But how will you learn if you don't try! After all most of the wiring I have gone through was aftermarket radio and CB that was very sub par which mat be causing some of the problems as well. Just another step in restoration!

[loy]

It could be that some of the Dash meters have corrosion inside of the units causing some of the problems. NOt sure if the water got up that high..

[zpizzaman20]

Much power goes through the headlight switch. If it has corrosion many strange things happen.