Troubleshooting Code 122

[Ross-N-Chicago]

I got this code the other day (TPS voltage too low). Swapped in a new TPS and the same code came up. I am not eletrically proficient, but is there a way I can follow up on this? I'll R&R another TPS but I'm not sure that's the problem since 4 th gear engages but is very rough. I think they may be related.

THanks...

 

[Opera House]

If you have a voltmeter

You can pull the connector and measure the pin voltage. One of the pins should measure +5V to ground. The TPS is basically a variable resistor. One end is connected to ground and the other is connected to 5V. A wiper measures the angle in betwen. Since the wiper never goes to zero there is always a minimum of about 0.5 volts. This tells the computer the sensor is connecter. So a break in the 5V or the signal wire going back to the computer will cause this code.

 

[Runnin'OnEmpty]

Just to add to what Opera House posted: One of the three wires going to the TPS is a ground wire. If you have a bad ground on this wire, you'll also get the low voltage code.

A quick and dirty fix for a poor ground wire is to splice in an extra wire and ground it to a nearby engine bolt.

 

[Opera House]

Just to add

A bad ground would give you code 123 or 124 a higher than expected voltage. Connector with the tab on the bottom: Bottom = 5V, Middle = ground, Top = signal back to ECM and on this line the resistance to ground probably is between 10K and 100K ohms.