uraniummetallurgist

Hi All:
I took my 928GTS out of hibernation after about 3 months of snow and bad weather for a short drive. After about 20 minutes the "Save Power" warning light flashed and the dash voltage meter showed about 10 v.

Quickly made my way home without issue and searched the 928 threads for some info. After checking the alternator belt (it's OK) and any apparent loose wires, battery connections, etc. it appears that either I have a bad alternator or a ground issue somewhere. I will check the battery voltage both with and without engine running to check the alternator and battery.

My question is can the various and assorted hard to get to ground points be gathered and re-routed to a more convenient location under the hood? I don't have ready access to a lift and it seems that if a good electrical connection from the various grounds to a central one that it would be easier to maintain a proper ground. I guess the downside is that diagnosing individual circuits for electrical issues would require going back to the original ground point.

Any input appreciated.

All the best,


Joe

docmirror

It's not an 'either or' situation. You most likely have ground loops, and possibly a bad alt too.

Attempting to gather all the various grounds into one location would likely add ground plane loops to the car, it would just move them from the chassis point where the ground is attached, to the wire extension you add to move the ground point together. So, no - it's a bad idea to extend the ground points for various systems by adding wire and rerouting. Clean them as specified in their location and reattach.

Edit: Start with the big ground wire at the batt. Sean has indicated that he's finding a lot of them with high resistance. Then, do the rest of the grounds, and check by charging the batt fully, and test it by starting and watching the voltmeter as you rev to 1800 then turn on lights, and AC, and seat heating. The voltage should not sag a lot when you load the system.

Ducman82

why re invent the wheel? clean the stock ground points/connections.

SteveG

If the ground strap is original, I would start by checking the resistance on it; replacing it. There may be corrosion beneath the insulation: cheapest easiest thing first. Then as stated the other ground points. There are about a dozen, I think there is a diagram in the New Visitor thread or a link to same.

Speedtoys

Do the required cleaning every 10yrs, and forget about it man.

WHy add wire, and make it all..well, slightly worse than perfect. in the end.

uraniummetallurgist

Thanks for the input from all! I will bite the bullet and do the ground cleaning and replace the alternator too.

All the best,

Joe

docmirror

I would diagnose before throwing money at the problem. Run the test I indicated and know what you know before swapping the alt.

Fully charge batt. Start the engine, and maintain 1800RPM. Note voltmeter indication. Load the elec system with AC, wipers, lights, blower, seat heat. You will see a reduction in the voltmeter, but it shouldn't be too much. If the needle goes down to 10 or 11, and does not recover, you have a 'charging' issue. Maybe alt, maybe something else. Alt can also be bench tested at O'Reillys.

Ducman82

never trust the gauge. check it at the jump post or CE panel with a volt meter. i make 14v, and the gauge says 12

docmirror

Trend is what we want, not cardinal value. If it starts at 12 and will stay near that loaded then the gauge is off, but the alt is working.

928NOOBIE

Freaking gauge ticks me off...it'll jiggle around just to be a jerk.