I have a 96 150 4x4 5.8 auto. My OD off light blinks sometimes(after running at hiway speed it will turn off temporarily). I have been told a wide range of answers to this issue, The only thing I've done is take out the sensor in the diff and clean it and the connector(which was clean). This is an OBDII, right? The trans seems to shift fine and the OD button works, no harsh shifts or clunks. Auto zone did not get any codes when they tested. What should I do to get the codes extracted?

 

i say replace the speed sensor on the top of the rear differential and the problem should be fixed.... sometimes when a throttle position sensor has an issue, the OD light will flash, but it'll shift hard when changing gears.... and yes, your truck is an OBDII, like mine is

 

The blinking light IS the code, (iirc). I do not know how to read it, but when the light is blinking, it should be blinking in a pattern. The pattern is the code and that will tell you what is wrong with the transmission.

 

Transmission codes are given when the computer is scanned. Yes, the engine computer.

 

Thanks for trying to help, but the blinking is constant and repeats in the same cadence with out pausing. It could not be a blink code.

 

Thanks, If I recall the transmission light was not flashing at the time he did the obd2 reading(it is intermitent). Some say it reads stored problems, others say the light must be on. I'm going to try again, maybe it will be flashing then.

 

It will store codes, the light doesn't have to be on.

 

Thanks, I've heard that before, as well as that it must be on. The question remains, what do I do to get them read? Shy of $100 at the dealer.

 

A computer scan will display them. I know in your other thread you said there were none, so there must be none. Engine problems will also cause transmission problems.

 

Thanks Sean, I'm going ahead with solving the EVAP purge/vent circuit issues, solve that and see if the "off" light quits blinking. In anothger post I mentioned that issue, code p0443, I can't assume that the EVAP system is unrelated to the trans monitoring.