Need help with engine codes

[Kevin92]

I got 3 engine codes codes 121 157 185. My car sometimes has a bad idle, I had mass air flow sensor and idle control valve changed. Can it be the throttle position sensor that can make those codes? Is there a way to check? Thank you.

 

[DOUG H]

121 is TPS signal out of normal range (could be high or low).
Verify reference voltage is correct. With sensor plugged in & key on engine off measure between orange wire & black. Should be 5V. Next check return voltage. With throttle closed( idle) between black & green wire it should be less then 1Volt .9 preferred. Slowley open throttle to full it should rise smoothly to 4.8V.

157 is MAF return signal voltage is low or most likely shorted to ground. ( below .4 volts) Reference voltage for this should be 12-14 V. Red to black with sensor plugged in. Return should be 1.2 engine off.

185 is also a MAF code for low voltage compared to TPS signal (lower then expected air flow compared to current throttle postition.

 

[Kevin92]

121 is TPS signal out of normal range (could be high or low).
Verify reference voltage is correct. With sensor plugged in & key on engine off measure between orange wire & black. Should be 5V. Next check return voltage. With throttle closed( idle) between black & green wire it should be less then 1Volt .9 preferred. Slowley open throttle to full it should rise smoothly to 4.8V.

157 is MAF return signal voltage is low or most likely shorted to ground. ( below .4 volts) Reference voltage for this should be 12-14 V. Red to black with sensor plugged in. Return should be 1.2 engine off.

185 is also a MAF code for low voltage compared to TPS signal (lower then expected air flow compared to current throttle postition.

Is there a easier way to find a spot to check for voltage?

 

[Kevin92]

This wire looks damaged can that be the problem?

 

[Kevin92]

I noticed this connecter next to the obd1 port looked corroded I put some electrical grease on it but I think it needs to get cleaned.

 

[DOUG H]

This wire looks damaged can that be the problem?

It is damaged & could be part of ( or all) the problems you're having. , but I'm not sure what that single wire is for? It looks like it could be shielded wire, or its been repaired before.

 

[DOUG H]

I noticed this connecter next to the obd1 port looked corroded I put some electrical grease on it but I think it needs to get cleaned.

I agree, both sides of this connector will need some attention.

Is there a easier way to find a spot to check for voltage?

It can be tested at ECU, but would need to find out the pin #s in the connector

 

[Kevin92]

I replaced the connector but it didn’t fix the problem. I took off the connector for the ecu and it has corrosion. I’ll try cleaning this off but I’ll need help identifying the wires for the connector on the ecu.

 

[DOUG H]

I replaced the connector but it didn’t fix the problem. I took off the connector for the ecu and it has corrosion. I’ll try cleaning this off but I’ll need help identifying the wires for the connector on the ecu.

What year is yours? I may have . Not sure how much they changed from year to year.

 

[Kevin92]

92

 

[Kevin92]

Here’s some diagrams from the book.

 

[coupe crazy]

There is a page that list all the pin positions

 

[Kevin92]

I had the Idle Air Control Valve replaced and The Mass Air Flow sensor replaced. I’ll try to clean up the harness and the pins first and hope that fixes the problem.

 

[Kevin92]

There’s only 1 pin for the sensor. How do I check voltage?