Electrical Gremlins

[CHaingKaiShek]

Hey all. Trying to make a habbit of posting here as I cannot seem to get too many replies about my truck in other..er.. areas I'm posting. I have a small, or large problem as the case may be.

After installing a new stereo, getting my wipers fixxed, getting the blower motor on my truck replaced, and a few other minor things. I've noticed that the ol' voltmeter is just dragging towards 10volts at night while driving, with the lights on mind you - sometimes the stereo but not lately. I'll explain that later. I've noticed while sitting at stop-lights, my headlights tend to flick in key with the turn signals - at first this was just minor, but is becomming worse and worse (now even MORE-so after I replaced the alternator).

Leading me to believe of course my problem was not the alternator in the first place.

So to see how much of a load I can put on the truck, I turn on the lights, Wipers, Hazard lights stereo and finally the blower. Now if I turn on the blower, the voltage meter will drop sharply, and my stereo will go off for a second, then come back on. Leading me to believe there is an amperage draw that the alternator cannot handle when everything is 'running'.

Could a bad ground cause this? My Neg.cable is hooked to the alternator bracket (OEM location I think.) Now normally I do not see this being a problem. However I have and ALUMINUM Manifold/waterpump now, while the factory stuff was Cast Iron.

Both the waterneck (Where one edge of the bracket hooks.) And the water pump (other half) have aluminium, plus a gasket, and a good amount of RTV. Normally, yeah I guess the bolts would be driving into the block/manifold and creating a useable ground - But for some reason I dont think it's 'quite right'.

Anyone else think the neg. cable could be the cause of my problems? It's really starting to annoy me.

Open to suggestions (By the way, yes the belt is at it's proper tension).

Jeff

[Prerunner1982]

i am having the same "diming" effect when i turn everything on.. i had to bump my idle up for the moment until it warms up enough for me to track everything down.. damn.. i need a heated garage.

[CHaingKaiShek]

Originally posted by Prerunner1982
i am having the same "diming" effect when i turn everything on.. i had to bump my idle up for the moment until it warms up enough for me to track everything down.. damn.. i need a heated garage.

Idle speed sadly does not make this problem any better. Simply allows me to turn on one more acc. before I notice it.

Jeff

[Prerunner1982]

well when you idle at 1000 rpm in park and 800 in drive.. it helps..

[Ryan Flowers]

CHaingKaiShek,

I had something like this happen on my 85. A few things I would try starting with the easiest:

• Trace the stereo wires and make sure it's grounded
• Try a distortion filter that hooks up to your stereo
• Check the NEG. wire on your battery & make sure it's grounded
• Try to relocate the alternator ground to the block or frame
• You could try to step up to a stronger alternator

You could also call the GM service center and they might be able to help you trouble shoot it over the phone (can't beat FREE profesional advice). Let me know if any of this helps.

[87gmc]

Yes your ground could be a huge factor in the way your electrical system runs i would try grounding it directly to your frame and see if that makes any difference, the other thing is you voltage reg may be going, out but it your reg is internal then that wouldnt be the problem becasue you just replaced your alternator.

[CHaingKaiShek]

Originally posted by Prerunner1982
well when you idle at 1000 rpm in park and 800 in drive.. it helps..

Hey.. I like my 650 in Park and my 550rpm in drive. :p

I didn't notice any change in the lights while upping the idle however.

As for the stereo. The Amp more than likely needs a better ground. (It's grounded between the driver's side seat 'track' and the floorpan (Bolt hole of course.)

The Alternator bracket bugs me (Because the battery cable is directly connected to it!) so I may relocate it to the frame and see if that helps.

Thanks for the info, I'll keep everyone posted.

Jeff

[82 Silverado 4X]

GM grounds our trucks to the engine block but over time alterations by previous owners (never us) eliminate this ground. Is the braided copper ground strap from the back right hand head to the fire wall still there and if it is, are the contact locations both on the head and the firewall both free of paint and corrosion?

[CHaingKaiShek]

Originally posted by 82 Silverado 4X
GM grounds our trucks to the engine block but over time alterations by previous owners (never us) eliminate this ground. Is the braided copper ground strap from the back right hand head to the fire wall still there and if it is, are the contact locations both on the head and the firewall both free of paint and corrosion?

Never was a braided strap connecting the block to the firewall/elsewhere when I got the truck. But I didn't have this problem (or notice it at least) for awhile.. It seems to be something new. (I.e. installation of the manifold or water pump.) I think the neg-cable relocation is going to help.. hopefully.

Jeff

[Blue Beard]

I just solved my problem like yours.

My truck had two grounding straps from the firewall to the engine, one on each side......

I had some wiring that was hard and brittle behind the right cylinder bank where it couldn't be seen that was shorting out......

Also the positive cable was hidden behind the exhaust manifold had been shorting out to the block for some time. It only had 4 strands of the copper wire holding it together.....wonder it didn't catch fire....

If you are dropping that much on your meter, a short would be the first bet....Be sure to check that stereo installation. Some of the installs have connected wrong to the fuse block and draw on the load.

[CHaingKaiShek]

Well I relocated the ground to the cylinder head (cast iron) not sure if this was the best of ideas, however it provided less resistance through the cable than being tied into the bracket.

On the way home tonight there was a loud 'pop' felt through the floorpan of my truck, as if it was a loud misfire or something hit my truck (going to inspect for damage when it's light.) But when this happened the alternator gauge dropped to about 8 volts and the lights dimmed, alot.

I figured I threw the alternator belt.

However a few more miles down the road (trying to limp it home) the lights returned to normal, the gauge still read low however. I got it home and popped the hood, and found all the belts in-tact still, no obvious damage to the engine compartment.

This is really starting to bug me guys. I'm starting to run out of ideas.

Jeff

[solidaxel]

You have a large voltage draw on your system. Start by checking the voltage at the + and - side of the battery with the engine off and the doors closed, then start the engine and take another reading at the batterymake sure EVERYTHING but the engine is the only thing on and take another reading at the battery then one by one take a reading and turn another Acc. on and the last thing turn your stereo on you will find it !!

[CHaingKaiShek]

I'm not sure on the importance of the engine's braided grounding straps (which mount from the cylinder heads or block to the frame) but my truck didn't have any.

I added two of those grounding straps (Head to frame on each side) and I've noticed and improvement. I also replaced my negitive/positive cables.

The wipers and the lights seem to draw the most voltage off the engine while running. So I'm going to have to go through the wiring harnesses tomorrow. But at least the lights aren't flickering.

Those grounding straps needed for early model chevy trucks? (mine is a 73)

Jeff

[solidaxel]

I think they are for every 12VDC system that has a Neg. cable from the battery to the engine and this connects the Cab-body to the chassis and provides a ground path back to the battery.