New Strange Tranny Problem

[vanionBB]

Ok, this one is wierd, bear with me.

The transmission shifts great, sounds great, and all around works great. The problem is the O/D Off Light. After starting a driving session, about 5 to 15 minutes into driving over 45mph, it starts flashing. When I turn off the truck the light turns off, then I can start it again and it wont flash again.

I tried to check codes but it doesnt throw a code, it just flashes after the first time I start it after it has been sitting for a while (cooled off). After cycling the engine off and back on the flashing goes away and everything works great.

What could this mean? I have driven 60+ miles without any flashing OD light, but if I let it cool off and then start it and drive it starts flashing but only until I cycle the engine off and back on. This is very confusing to me. Any help would be appreciated. Thanks in advance.

Cheers!

 

[jimbo74]

how many miels are on the truck? the od flashing light indicates a problem, now there could be no problem at all, and it could jsut be electrical, but usually it indicates the tranny is beginning to have issues

 

[vanionBB]

over 200,000 miles on the truck

 

[vanionBB]

its really wierd, if I cycle off and on the engine the OD light never comes on again, at least not in the hours I drove it... It only happens after it has been sitting for a time (probably cools down some).

I put it in neutral while driving on the freeway, then turn off the key, and turn it back on, start the truck (while going 60) and the OD light stops flashing. It wont return until I turn off the truck and let it rest for 30 minutes or so.

 

[Wrench]

OD light flashing

Did you use a trans capable scanner when checking for code(s)? The run of the mill scanners won't work. When the od light starts flashing the system has gone into limp mode. The reason the od light stops flashing when you turn the ignition off is you are resetting the Pcm but the code is still there in memory. It is not a good idea to drive the vehicle very much while the od light is flashing. Fluid and level good?

 

[vanionBB]

Wrench, thank you for your reply. The fluid level is good. I replaced the tranny filter, and was about to do a flush but then the light flashes so I dont really want to put synthetic in there if it might be going bad.

Could it be bands? Everything about this truck is very good, the engine is good, body is in good shape, I even checked the rear axle and the transfer case, all very clean and the gears dont seem worn out at all.

The vehicle has over 200,000 miles but it seems like the previous owners took great care of it.

Trans capable scanner? I do know that there was a problem with the speed sensor, that I have since fixed, and it did store a code in the comptuer that I was able to read out. Also, when the OD flashes the transmission I dont lose overdrive. It usually stays in 4th gear (overdrive) so I am not sure...

The scanner I used is the one that Schucks has available for free. Today I drove it all day with only the first O/D flash. The rest of the day there were zero error codes / flashing O/D lights. I am wondering if it is a glitch in the system?? I am at a total loss here...

Thanks

 

[vanionBB]

I just received my secondary tranny filter kit and plan to install it tomorrow. I still have no idea what is causing my O/D light to flash on and off. If anyone has any ideas please let me know. Thank you

Cheers!