SES when using AC

[ford2688]

Hi,
On my 1998 s10 2.2 I sometimes get a SES light about 20 minutes after turning on the AC.
The idle goes to 1100rpm as it should, but sometimes stays at around 1500rpm.
The SES light usually goes out by itself after being parked a while or overnight.
I have a 122 code which is Throtle Position Sensor circuit low input.
Will changing the tps fix this?
Angelo

[old_master]

If the TPS is bad, it will fix it DTC's tell you what circuit has a problem, it does not tell you what the problem is, or what part to replace. Checking the circuit will tell what the problem is. P0122 indicates low input voltage and can be caused by a number of things. Do you have access to a scan tool that will dial in to the TPS circuit?

[ford2688]

No, all I have is this cheap code reader.
I might take a chance and replace the TPS.
If I bring it to a shop they'll most likely change it anyway, plus whatever else they can think of.
Angelo

[old_master]

It's quite possible the TPS will solve the problem, but don't get discouraged if it doesn't.

[ford2688]

If that doesn't fix it, what should I look for next?
Angelo

[old_master]

Without a scan tool that reads TPS voltage directly, you'll need to back probe the TPS signal wire and check voltage while moving the throttle open and closed. The reference voltage wire and ground wire can be checked by disconnecting the sensor and probe the harness connector. The signal wire should read approximately .2 to 4.5 volts depending on throttle position. The ground should show less than 5 ohms resistance to vehicle ground, and the reference voltage should be approximately 5 volts.

[ford2688]

Changed the tps, that fixed it!!!

[old_master]

Glad you got her fixed, and thanks for posting back!