Howdy all--

Been chasing this gremlin for quite some time and am now at a brick wall.

Voltmeter, at one time, would intermittently cycle to a "high charge" condition and back to the normal range. This happened off and on for most of the year. When I ran another "ground" lead from the alternator to the PCM, it seemed to help for a while but then continued to sporadically go to an overcharge condition.

Recently it has not been cycling back to the normal range and stays on the high charge.....and thus cooking my battery. So last week I replaced the alternator and put in a new battery. No dice.....stays pegged on a high charge.

Just put in the new PCM today. Started right up.....voltmeter read dead center for a few minutes.....then drifted and stayed pegged on high again.

Got out on the road and drove it a little bit in the hopes it would right itself, but to no avail.

What do you think my next place to look for the fault should be?

CHEERS guys....

Lance-

 

check all the grounds on the vehicle

 

How many grounds are there? Is there a location guide reference floating around somewhere?

Thanks.

 

there is a service manual in the faq thread near the top of the forum

 

Replace the alternator.


The PCM only regulates the power into the main electrical system, NOT the power going to the battery. 99% of all the electrical under and over charging is battery or alternator related. Clean the posts and terminals. The Alternator is regulated not to exceed 14.6-14.8 volts. If it goes over this, and you can verify it by testing voltage between the battery posts during this condition, then the alternator is dead and most likely took out your battery to boot. Go get a new DuraLast Gold battery (or what ever you like) and a new alternator (not rebuild). Where you have already replaced the PCM then shoot directly to the alternator and battery. Ensure that you get the biggest battery that fit's as OEM in your truck.

 

like hydra said, check the actual voltage w/ a voltmeter, and then if its actually reading higher than it should replace the alternator, if the voltmeter is reading in range (the extra one you attached) and the in car one then your voltage sensor needs to be replaced

 

Thanks guys.....

So new battery, new alternator, new PCM---still charging high, then look at the Voltage Sensor?

 

check it with a regular voltmeter, im not sure where or how they have the voltage gauge hooked up to the system

 

The voltage sensor is in the PCM, no change there.


Are you sayin there's still a problem, or have you replaced the parts I suggested?

 

Okay, here is where I'm at today....upon startup, the interior voltmeter read normal and a reading between the battery posts read 12.8v. Stayed steady while running in park and readings did not fluctuate. Thought the problem was fixed. As soon as I put the vehicle in gear to drive away, the interior gauge climbs to Full High. Reading at the battery posts is 18.9v

The battery is brand new. The alternator is new. The PCM is new. The battery tray temp sensor was replaced not too long ago.

So tomorrow is my "check the grounds" day. I had a quick look tonight at the main battery ground and it looks fine, but I guess I need to unhook, clean, reinstall with some dielectric grease and work my way through the ones I can find.

Any additional suggestions are greatly appreciated....

Lance-