O/D Light Flashing On and Off

[LJSOU812]

Just finished with a rebuild on a 4r70w transmission ('05), and now the O/D light wants to start flashing after only a few miles at highway speeds. I have a small hunch about what might be causing it, but I was hoping to get some input from some of the pros out there before I attempt anything.

(and yes the fluid level has been checked and is full)

 

[BrooklynBay]

Check the electrical connections, and find out what the code numbers are.

 

[LJSOU812]

The codes you mentioned ... are you talking about ones that I can scan with a simple code scanner or a more expensive version that can do more than tell you what turned the check engine light on? The check engine light never turns on, and I can get the flashing o/d light to temporarily turn off by shutting the vehicle down and then restarting it. Of course it comes right back on when I get back up to speed.

I'll check the electrical connections again, but I'm not sure how I am going to check for any codes it might be setting with the code scanner I currently own.

 

[BrooklynBay]

You might need a better quality scanner.

 

[LJSOU812]

This is the scanner I have: http://www.amazon.com/Actron-CP9145-AutoScanner-Diagnostic-Capability/dp/B00020BM2S/ref=sr_1_12?ie=UTF8&s=automotive&qid=1271947155&sr=1-12

If this is not adequate, where might I find one that can do what I need?

 

[BrooklynBay]

This might work for you: http://www.explorerforum.com/forums/showthread.php?t=223600

 

[LJSOU812]

Thanks for the info. Makes me sorry I also bought the Actron ABS code scanner a few years ago. I wish I had known about this then. Oh well, what can you do?

 

[LJSOU812]

As an update ... I was finally able to borrow a Snap-On Solus to scan the transmission codes and found out that the torque converter wasn't locking up. Not sure how I didn't notice it while I was driving it, but anyway.

To this point I have tried a new TCC solenoid and a new (rebuilt) torque converter, and neither has corrected the problem. Right now I have the valve body pulled back out to reinspect it for damage of any kind. I'm not really finding anything wrong with the valves, springs, or valve bores. The check balls are also still in good shape and are where they belong (all eight). I have also checked and rechecked the electrical connections in and around the transmission hoping that maybe something was just loose or maybe not connected correctly, but that did not turn anything up.

Is there something I am missing that could possibly be causing my problem?

 

[LJSOU812]

FINALLY A CONCLUSION!!

After a couple weeks of blindly chasing my tail, I have finally figured out what was causing my o/d light to start flashing. As it turns out, the brake light switch attached to the brake pedal went bad which interfered with the pcm's ability to communicate with the tcc solenoid causing the torque converter to not be able to apply (lockup) while driving in overdrive.

All that work and rework for what turned out to be a simple $20 (or so) part that takes five minutes to replace.

 

[CGordon]

Nothing like learning the hard way... hehe... I'm in a very similar situation right now also.

Glad you found the solution!

All too often people fix the problem, but never post back with the fix. So a big thanks for posting how you fixed it. Thanks!

 

[BrooklynBay]

Thanks for the update!

 

[IronIndian]

Glad to hear you're back up n runnin! Thanks for the update and fix!

 

[roman13]

I have a 2004 ford explorer, l change the solenoid module (EPC), while driving a few miles the O/D on and off, the engine revs up to 3000, but then fall to 2000 and remain in that range. My scanner is a ( Actron CP9135) OBDll, not giving code, the information than provide is no return code