Ok so I have a 99 expy 5.4l with roughly 180k on the tranny and body. My wife's od light on the shifter started flashing bout 2-3 weeks ago. It doesnt do it all the time tho. I searched around a bit and decided to change the fluid and filter with nothing changed when I did. Fluid looked pretty clean normal wear and tear fragments on the magnet. Finally had a code p0708. It said trans position sensor. Changed that out and still have the od light flashing. I have no clue at this point. Its not slipping it'll only bang a but upshifting. Any help please

 

If the sensor didn't fix it the problem is almost certainly the wiring between the position sensor and the computer.

 

Your awesome. Thank you so much I really appreciate the help. I'll be chasing wire tomorrow in a tight spot with Hugh hands lol. Again thank you. By any chance do you know if I would fail emissions for the tranny code? Its not part of the emissions system. Can't find any laws on it for ct.

 

I've never lived in CT so I don't know anything about their laws.

If you are checking the wires by looking at them let me save you some time. You won't find anything but the most obvious problem. You need to check them electrically with a meter.

 

Ok I've tested a few things with my volt meter but how would I go about this? This is starting to walk the line of not that I don't know what I'm doing but more of the damn i hate freaking thing. But any and all help is awesome. Oo my wife noticed last night that when the tranny light flashes and it acts up, it sounds like a whinning noise is coming from the tranny.

 

You only fail if the CEL is on.
What is OBD? « CT Emissions

 

Unplug the VSS and unplug the harness at the computer.

Get a jumper wire so you can test from the computer connector to the VSS connector.

NEVER put a probe into the end of the connector that makes the connection. That will open the pins and they won't make a good connection. It creates problems where there were not problems before. Always probe the back side of the connectors.

Check each of the wires to the VSS for continuity, for a short to a power wire, and a short to ground. Also look at the connectors and see if there is any corrosion on the pins.

 

Sitting getting emissions done now, hope it passes. But will check out the wiring when I get it back home. Thank you again. And will let you know if it passes or fails. The cel was off on my way here hope it stays off as there testing it

 

Ok well it failed. P0708 transmission range sensor circuit high is what ct emissions computer said it failed for. Chasing wires is in my imminently in my future.

 

Did you point out their website conditions for test failure, none of which applied to you?

 

Was your Check Engine Light on while the engine was running?

 

The tech himself said it shouldn't fail for anything that has to do with the tranny but ct doesn't care. When I pulled it in the bay it was off, so either the obd computer forced it on or it came on by itself. Which I've never had it come on with the tranny problem if its sitting at idle. So they gave me 60 days to fix it and I don't have to pay for the retest. A buddy of mine said to change the speed sensor, could that cause this?

 

No, that couldn't cause a P0708. You'd be more likely to have it turn off by waxing your truck. Don't listen to that buddy, he doesn't know how this works and just likes to spend your money.

This code CAN turn the check engine light on, even if it is sitting at idle.

 

Yes it seems that way since he also ran over my freaking volt meter pulling his bike into my garage. Going to get a new one then what should the meter read going threw the wires?

 

It should read nearly zero ohms when testing continuity. It should read open circuit when testing to see if there is a short to ground or to power.