1997 Limited Overdrive issues - Need an expert!

[tobes484]

Hey all!

I am generally able to figure out issues myself, but I am totally stuck here.

I have a 1997 4 Rummer Limited with about 230K miles on it. I don't drive the truck a ton, as it's my winter car, but I did notice that my overdrive stopped working. The trucks shifts through 1-3 with no issues. Once it stopped working, I did a transmission flush and then started to do some research to see what I could check.

Here is everything I have done to test, but to no avail:

1. Performed manual shift test and it worked fine for 1-3, never went to O/D
2. Brought vehicle temp to 200 degrees (as measured through the ECU on a Snap-on Ethos), never went to O/D
3. Ohm'd out the trans temp sensor after warm. It measured 713 which is right inline with the OEM warm resistance recommendations
4. Using the Snap-On I confirmed that the O/D button was working at the ECU. I also verified the ECU knew what gear it was in while shifting.
5. No change happens when the O/D drive is pushed, except the O/D Off light illuminates
6. No change happens between power and regular modes

The only modification to the truck is the "Blue-wire" mod. Additionally, there are no check engine lights, no pending codes, and no transmission codes.

So...What have I missed?! What else can I check to get my O/D back?

Thanks in advance!!

 

[Down by the Water]

OD not working

Hey, I see that this thread is a couple years old, but did you ever figure out the issue. I'm working on a similar problem with my '96. It will occasionally not shift into OD. The fact that it's an intermittent issue makes it a lot more difficult to deal with? Also, I thought the manual shift pattern is L=1st, 2=3rd and D=4th or OD. Is that not correct? I guess I'm not completely clear about the shift pattern??

 

[Black798]

The shift pattern is L=1, 2=1-2, D=1-3 the OD button controls weather or not it will continue from 3rd to 4th (od) when in the D position. If you do all the diagnostics as the OP and find the same results I would point to the lock up solenoid in the trans as the culprit.