Hi all,

I am new to this site but cannot seem to find an answer to my dilemma. I have a 97 PSD 2WD with a 6" lift and 35" tires, 6 position chip and 4" straight pipe. Truck has 260,XXX miles and has had zero issues since I purchased it (at 220,XXX miles.)

Just this past Saturday while driving it I noticed that it was not shifting into OD when it should and the ABS light came on intermittently. I searched and found a write up about the rear diff speed sensor so I replaced that however the issue still exists but the ABS light does not come on anymore. The trans will shift into OD if I accelerate at highway speeds but it shifts right back into passing gear. Fluid is good and I have tried all of the settings on the chip to no avail. Trying not to take it to the mechanic as I don't think this is a major issue.

One recent change which may or may not be the issue is I replaced all the rear lights with LEDs. I know this can cause an ABS light as the system doesn't recognize proper load on the electric system but don't think it would be related to the transmission. There are no trouble codes or idiot lights on and no other known issues.

Anyone have ANY ideas???

 

LED on tail lights is your problem, what you describe as OD is actually the torque converter not locking up. There is some LED design with resistors for our trucks, maybe someone here can point you where to get them.

 

So why would having LED lights cause my truck not to shift into OD? I just don't see the correlation?

 

Because the rear tail light including the cab stop light send the signal to the pcm every time you press the brake it sends the command to un lock the TC but in order to function the light bulbs themselves work as a resistor, maybe someone can explain this better than i did.

 

Wow! Truly a complicated system. I found some resistors on Amazon. I will get to installing them this weekend. Thanks for the info!

 

*****UPDATE*****

First off thank you for the info. It was the tail lights and a resistor on each brake light has corrected the problem. They say to mount them to metal which you should definitely do because they do give off some heat. That being said, they don't get ridiculously hot where they would melt any wires in the general vicinity. I drove in bumper to bumper traffic for over an hour and while they were quite warm I could still touch them without getting burned.

I am thinking of replacing my front turn indicators, parking lamps and headlights with plug-and-play LEDs and was wondering if there is any additional parts I should order so as to not create anymore problems (i.e. new LED headlights and now my truck won't turn left).

 

Can you elaborate more about what tail lights and resistor did you install. I want to install led lights in the reverse bulbs only. I dont know if that needs resistors too?

 

Reverse lights do not need resistors. They are only needed on brake lights.

 

Mark you are the man! Thanks a lot