View Full Version : trouble regulating voltage on T2 car

01-25-2006, 01:38 PM
New to turbo dodges.....looking for a couple ideas.

A buddy just picked up an 87 charger GLHS....car ran well when purchased...he put about 30 miles on it before he started having some problems. Car sat outside for 2 yrs before he bought it...but was started and ran occasionaly by the previous owner.

PO told us it would occasionally sputter and he would have to hit the passenger side kick panel and it would clear up. Well...it started sputtering after the 30 miles my buddy drove it...we pulled the kick panel to reveal the logic controller. It was a NAPA remmanned unit. Pulled the 2 plugs to find water in them....cleaned, dried, and put back together with dielectric grease.

Car started up and ran smooth.

At this point we noticed his volt gauge was reading low. So i checked the voltage at the battery and sure enough...it wasn't getting a charge from the alternator. A quick trip to autozone and an alt test showed it was junk...got a remmanned unit and we're on our way. Swap alternators and start the car up....14 volts at the battery....cool. Had him hit the lights and heater...still 14 volts. Cool. Drive the car outside in the parking lot and his gauge dropped down after 2 minutes of driving....checked volts at battery and alt not charging...hmmmm..so we gave up for the night.

So the car sits outside in the rain for a couple days...and we have to jump start it...starts up fine and runs good...getting 14volts...car idles for 2 minutes....all is good. Starts to give it gas and the volt gauge increases with engine rpm...goes up to 17 or so volts....not good. Shut it down, pull the REMANNED NAPA power module and clean both plugs and a couple battery grounds to the fenderwell. Both plugs in power module are wet and grounds are rusty.

Start car back up after re----'y....14 volts....ok....idles for 2 min....holds pretty steady. Gives the car some gas...and the volts increase up to 17 or even 18. (now in the initial car start up...the car can be rev'd and the volts DO NOT increase with rpm...stay at 14...then after about 2 minutes....it can no longer regulate volts.)

What the heck?

So i'm thinking the following.....bad NAPA remmaned power module

Or bad NAPA remmaned logic controller

Or bad wire somewhere. (not sure of this one)

Any thoughts/opinions/suggestions welcomed, and sorry for the long read.

01-25-2006, 01:45 PM
If the chagring system is functioning normally, you could run an external regulator to solve your problem. The power module does indeed regulate the voltage, so that could be the problem.

I switched to the newer nippodenso alternator in my GLH which really helped the situation, as the stock bosch alts blow. Check out my install at www.omniglht.com You will probably fry the fusable link when doing this, so you will have to run a wire from the alt output to the battery sooner or later from all that I have been told.

The water coming into the car and getting all over the LM is probably from where the fender and firewall seal up under the cowl. The sealer shrinks up and cracks in that area allowing water to get in.

good luck.

01-25-2006, 02:15 PM
I can alleviate the water problem...that's not a concern as i'll just wrap plastic around the LM to keep it dry....and oddly (or maybe not...remember i'm new to TD's)...the PM plugs were pretty wet as well. I'll have to be a little more creative in keeping this dry due to the location.

Also...the only purpose of the air running through the PM is for cooling, correct?

As for external regulator...i'd rather get the factory stuff working correctly. The alt itself is good as it puts out more than enough voltage. And due to this, i'm ruling out a bad wiring connection as i would only see 14v or less...not more.

Thanks for the help so far....

01-26-2006, 12:43 AM
You really don't need the hose going to the PM. It is for cooling, but no one has ever had a problem that I have read of with not running it.

I would fix that water leak even if you protect the LM in plastic, as it is suspected to be one of the main causes of the notorious L-body floor rot.

The voltage is regulated by the PM, so if it fails, you will need to get another one as far as I know.

01-26-2006, 12:22 PM
Someone posted a good tech article on Turbododge....i'll see if i can diagnose the problem from that page....thanks for the help.

As for fixing that leak...this car already is too far gone to repair that cowl leak...plans are to swap everything over to an omni....too bad too...cause it's a numbered car that is practically all there.

01-31-2006, 07:16 PM
Could be a shot in the dark but.... I had a similar charging problem on my 89 Daytona. I would see 17-18v sometimes, and other times it would charge 14v. Turns out, the bolt that attaches the ground wire to the drivers side of the head was loose. Everything has been fine since I tightened it up.

02-20-2006, 04:51 PM
Just figured I'd update this....problem turned out to be a bad PM. Everything else in it worked fine except it couldn't regulate voltage. We're going to wire in an external unit for $15 as a remmaned PM is $100.

Thanks to all who helped.