I'm having an issue with my TPS reference voltage- it's only reading .89 volts into the tps, and so the voltage out only reads from .12 to about .6 . I traced the wire (should be around 5v, correct?) to the ecm and that voltage is the same as measured at the sensor.

Basically, it looks like the ecm is sending .89 volts instead of 5v to the sensor, which in turn is reading very low, throwing the TPS low code as well. Engine isn't running well either, as you could imagine.

Car is a 93 LT1 with an STS and new tune, which shouldn't affect this as far as I can tell.

So is something wrong with the ecm or is there a blown fuse or what? I'm pretty confused.

Thanks for the help.
Kyle

 

try unplugging TPS sensor when checking for the 5volt reference?

my 93 shop manual shows:

TPS Sensor: Pins
A - gry 5v ref
B - blk sensor ground (also shared with ECT sensor)
C - blu TP sensor signal

from the way you described how you tested it, you either have an open or short to ground in the 5v ref circuit, or faulty pcm according to my DTC 22 flow chart.

if faulty pcm is truely the case, the MAP sensor has its own 5volt reference, maybe you could splice off it's ref and feed it to your TPS sensor. the map sensor's 5volt ref is the gry wire pin C, or C7 at PCM connector.

good luck