Some sort of electircal issue...

Sodbuster Jr. · Jan 24, 2012

Ok so the past few days I have noticed that when my TC locks my voltmeter takes a huge drop. When the TC locks it slams in and usually prematurely. I'm thinking it is a grounding issue some where in the harness. Just wondering what you guys think, and could maybe point in the direction of where to start. It would be much appreciated gentlemen.

Tom S · Jan 24, 2012

Do you think the engine RPM suddenly dropping is the voltage issue? This is a heck of a mystery.

Pstroke96 · Jan 25, 2012

what rpm is the converter locking at? are you going off the gauge on the dash? it itsnt a precision instrument

Sodbuster Jr. · Jan 25, 2012

I first though the same Tom. I have 3.55 gears and it usually locks at 45 mph, and about 2000 rpms. With it acting up it locks at just a touch below 40 mph and about 1700 rpms. When it shifts it just lugs, but the volts come right back. I am not very good with electrical, especially wiring harness's. Any ideas how I could trace something down. Could there be a grounding issue that is acting like how a TC lock up switch would work?

Pstroke96 · Jan 25, 2012

i dont think that is to low out of range for a tc lockup. under light load low throttle. if the drop in rpm's is causing the drop in voltage id check the alternator first since thats the only thing that directly relates voltage to rpm

Sodbuster Jr. · Jan 26, 2012

yeah i was planning on doing that tomorrow. I guess it'll give me some place to start.

Pstroke96 · Jan 27, 2012

did you make any headway?

Sodbuster Jr. · Jan 28, 2012

Well everything on the alternator checks out fine. I have gone over every harness to the trans looking for any wires that were/are chaffed, but nothing. Unless I have overlooked something maybe the volts are just dropping due to rpm drop.

SPEEDDEMON31176 · Jan 29, 2012

You should not see a dramatic voltage drop when the tc locks. I would pull the connector for the solenoid pack on the passenger rear corner of the trans and check for moisture, corrosion, etc.

Sodbuster Jr. · Jan 29, 2012

Okay will do once the weather subsides here. I also pulled a code from the truck last night that said there was an issue with the transmission temp sensor. P[FONT=default,Times New Roman,serif]0713 TFT Trans fluid temp sensor ckt high input Open circuit, biased sensor, PCM, short to power.
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SPEEDDEMON31176 · Jan 31, 2012

You definitely have an issue with the connector that I mentioned. It is behind a small shield that is held in place by two 8mm bolts. You will need a mirror to check the transmission side of the connector.