6 volts at tps reference signal

[spastik monkey]

So I keep throwing the low tps voltage code. I go out to adjust the tps. I'm reading 6 volts as a reference signal. With and without the sensor plugged in. Reading 12.74 volts at battery. at one point it dropped to 5.12 volts then went back to 6. What would cause this? I know the ECM puts out the ref signal

 

[sweetk30]

check all your frame to body and engine to body grounds.

someone might have left one off. or one could have rotted off.

grounds play a big part in signal feedback to computer.

 

[spastik monkey]

Grounds all look good. Stock wiring is a little small for my taste, but nothing is rotted off.

 

[GRINCH]

The reference signal (gray wire) is supposed to be 5 V and at idle the tps (Dark Blue) is 0.54 =/- .07 and about 4.5 at WOT.

I assume you are getting a code 22..

Trouble Code 22 indicates that the Throttle Position Sensor (TPS) is reading abnormally low. TPS volts should be close to 0.42 V at closed throttle and rise smoothly in about 0.02 volt increments to a maximum reading of about 4.85 volts at WOT.​

The conditions for setting this code are:​

• the engine is running, and
• TPS reading is < 0.20 volts

Note: During a Code 22 condition, the ECM uses a default TPS value of 2.6 volts. This will cause the engine to idle very high.
​

Typical causes for this code include:​

1) Maladjusted TPS
2) Defective TPS
3) No +5 volt reference to TPS
4) TPS-return to ECM is shorted to ground or to sensor ground
5) Defective ECM​

NOTE: The TPS must be adjusted to about 0.42 volts at closed throttle for the ECM to auto-zero properly. If necessary, adjust the TPS to bring the voltage up or down to this value at closed throttle.​

 

[spastik monkey]

Well I know what the code is and why. I'm just trying to figure out how to fix the reference voltage to read 5 vdc so I can set the tps.

 

[GRINCH]

Well I know what the code is and why. I'm just trying to figure out how to fix the reference voltage to read 5 vdc so I can set the tps.

Just making sure you understood the TPS system.

That reference voltage is also shared with the Map sensor. Pull that connector also and see what you get with them both disconnected.

GM made these TPS's nonadjustable. http://coloradok5.com/forums/showthread.php?t=255706&highlight=tps&page=5.

Not sure the high reference voltage is causing your "Low voltage" code to be pulled. You never did post your voltages at idle and WOT.

 

[spastik monkey]

Mine is adjustable, it's the holley one that comes with the holley throttle bodies. The lowest it will let me adjust it to is 1.12 volts with the 6 volt ref signal. The truck is running good for now, but I'm gonna have to fix it soon.