Help me figure out voltage drop problem please!

[SlickTR]

My voltage drops at WOT, down to 10.8 volts its fine driving around 13.3 to 13.8 usually but drops when I get on it. I checked all the grounds and even ran a bigger gauge wire from the alternator and it didnt help. So I have a few questions

What else could cause this?

Can the alternator be "bad" and not keep up at WOT but be fine driving around?

I noticed the dash battery light does not come on when I turn on the ignition. I figured the bulb was burnt out, but could this be part of the problem?

 

[nick368]

Dash could definitely be part of the problem.

 

[rodman99999]

I noticed the dash battery light does not come on when I turn on the ignition. I figured the bulb was burnt out, but could this be part of the problem?

The voltage that energizes the field in your alternator has to pass through that bulb. YES- replace it!

 

[SlickTR]

Alright guys, I'll replace it and report back Sunday

 

[TurboV]

x2 on the bulb. Its easy enough to do, i just went through all of mine. Step 2 may be Alternator check at Auto-zone.(theres no charge to check it). good luck, let us know.

 

[PaCemkr86]

does your car have a volt booster on it ?

 

[SlickTR]

does your car have a volt booster on it ?

No I dont have one on the car.

 

[turbojd]

And if the new bulb still does not light on the dash when you change it and your alternator checks out to be good, you could always bypass the dash "volt" light with Caspers electronics "alternator field fix kit" all plug-n-play.

 

[quicker6]

Check the positive battery cable to the starter. If it has a small area melted off through the insulation it will contact the header upon WOT resulting in a voltage drop. It gets worse as you drive it more and more.
Good luck

 

[SlickTR]

OK, I replace the bulb and it still did not light up so I tried removing the cluster to get in behind it and see what is going on but it didnt really seem to want to come out. After I messed with it a bit I noticed now my oil light does not come on either now. I guess some wires are loose back there. How do I get the cluster out to access the wires back there? It's a Digital dash car.

 

[SlickTR]

I got the cluster out, wow that was a pain in the ass...anyhow I guess I'll try cleaning the contacts

On a side note anybody know where I can get the clear plastic piece that goes over the front of the cluster, I screwed mine up

 

[turbogronk]

Cluster window

GBodyparts.com has the cluster windows. Have to drill the hole for your trip odometer.

As for the dash, yep. It's a pain. The flexcircuitry on the rear can be flimsy & easily damaged. Examine it for cracks if cleaning the contacts doesn't work. Be sure to clean the press-on connector's contacts and your bulb hole contacts both.

 

[rodman99999]

I got the cluster out, wow that was a pain in the ass...anyhow I guess I'll try cleaning the contacts

If there is any damage to the contacts, etc.: Caspers's Electronics repairs digital dash clusters. Any broken contact in that Alt light circuit(or the bulb itself) will affect your alternator output.

 

[SlickTR]

Alright I fixed the volt light, it comes on now, the cluster just wasnt sitting on the plug very well, mainly due to one of the mounting bolt locations being broke off. I also inspected the wiring going to the starter and it looked like someone had the battery mounted in the truck at some point. that wire was still hooked up to the starter. I removed all that as the connection was frayed and there was a spot were the wire had melted hitting the exhaust. Well after all that my problem in not fixed It got better, I gained about a volt back, it only drops down to 11.8 or somewhere in the twelves now. Guess I'll have the alternator looked at next.

 

[quicker6]

Dont forget to check belt tension too. For it to act up at only WOT also could mean that your belt is slipping under the rapid increase in engine RPM's. I also had the same problem with a worn out serpentine belt.

 

[krom]

Check the positive battery cable to the starter. If it has a small area melted off through the insulation it will contact the header upon WOT resulting in a voltage drop. It gets worse as you drive it more and more.
Good luck

Been there, fixed that.

 

[SlickTR]

Dont forget to check belt tension too. For it to act up at only WOT also could mean that your belt is slipping under the rapid increase in engine RPM's. I also had the same problem with a worn out serpentine belt.

Belt looked fine and is tight, I dont think it's slipping. I gave it another run for the hell of it and noticed a new symptom since I have the volt light working, The light flickers when I go WOT. Does that point towards anything?

I'm going to have the alternator checked out by a good automotive electrical shop next, I cant dont know what else it could be at this point.

 

[brian]

Belt looked fine and is tight, I dont think it's slipping. I gave it another run for the hell of it and noticed a new symptom since I have the volt light working, The light flickers when I go WOT. Does that point towards anything?

I'm going to have the alternator checked out by a good automotive electrical shop next, I cant dont know what else it could be at this point.

Do you still have the factory alternator in the car?
If not, that is probably the issue.

I had VERY similar issues as you describe. Put a known good original alt on and problem solved.
Aparantly it is the replace regulators used by rebuilders. Install and original GM reg, and you should not see this issue. Or get a good used reg from a rebuilder.

 

[russgill]

Was there ever a resolution on the problem?

 

[SlickTR]

Was there ever a resolution on the problem?

Not yet, I havent had time to mess with it, I've been out of town for training (military) plus some other issues come up, like my transmission. I checked out everyting I could think of though, I believe it's just the alternator not being able to keep up.