NEED HELP! Q guy down!

[elwesso]

so a friend of mine is stuck in the middle of BFE with a 94 Q.. What happens is the car drives fine for a while (he drove 3 hours sans problem) and then it throws a revolution sensor (code 1) and speed sensor (2).. Unplugging the battery for a bit has helped in the past, but this time it doesnt seem to be doing it..

No signs of leaks from any of the sensors.. Does anyone have any ideas what could cause an intermittant issue like this...? If theres some way to trick the trans to get out of failsafe that may be good so he coudl at least get the car home... Right now he's coming back to my place so we can fix this thing.. He'll be a few hours so i have to get an idea what we're dealing with because we have very limited time!

[Q45tech]

Other than checking transmission connector for corrosion? One usually replace the sensors first then tcu in diagnosis chain finally transmission.

With Consult you can view sensor voltage in detail as seen by tcu since the ecu is not throw speed sensor codes?

[elwesso]

whats weird is when it starts working again, it will work fine for like 3 hours on the highway and then fail again. That sorta sounds more like a connection issue than an actual sensor issue, agreed?

[qsiguy]

what about unplugging the TCU and running in 3rd gear until he gets home? Take it easy off the line and keep the top speed under 65 and it should be safe, right?

[elwesso]

thats very much a last resort... He's got a long trip to go, so we'll see. Ill get under the car tonight and we'll see what comes up.

[3Q Jay]

first establish voltages on the system. when the battery voltage gets in the 12 range (engine off) strange things can happen with the computers.

what are the observables from a driving standpoint?

[Q451990]

I would think it's odd for both sensors to fail intermittantly at the same time. I agree with 3Q Jay about checking the voltage... but I would think the usual alternator warning signs would show up in that situation.

Heath

[elwesso]

so heres what the car does... When it goes into failsafe, he'll be driving along his merry way and then all of a sudden it will downshift into 2nd gear. he said it does it really smooth like you wouldnt really notice it but its pretty intense when it happens at 75MPH..

He checked voltage while driving at the TCU and it seems normal. of course when he was driving it the car behaved normally while testing the voltages..

The only thing he didnt check that I wanted to was the resistance value on the revolution sensor...

[Rex]

Voltage sounds like a likely culprit. The car had mainly sat for the last 4 months with barely any use since early/mid February. I think he's going to try a new (full charged) battery.

THANKS Wes

[elwesso]

when I saw the car it didnt exhibit any signs of bad voltage, and it ran like a bat out of hell!! I even threw it on stage III.

[Rex]

As weird as this may sound, unlocking the doors with the remote seemed much "quieter", like the battery was kind of low. It's hard to describe, but usually when I would unlock the doors with the remote, you could "hear" the doors unlocking from >30 feet away, and recently just barely hear it when beside the car.