I'm almost at a loss over here. My XJ needed a new head gasket. I replaced the gaskets water pump inlet tube hoses, and other small stuff. Went to start her and it flung straight to 2500+ RPM. I quickly shut it off and inspected. I've connected, disconnected the TPS MAPs and IAC. I had codes 505, 123 and 108. I replaced the TPS and MAP. Now I only have 123 which is TPS HIGH VOLTAGE. I can't figure this out. She runs to 2500 and doesn't want to come down. What could I be missing?

 

Did you replace the IAC? If so you need to adjust it before you put it in otherwise it'll do that. You may be way ahead of me there but that's the the only thing from off the top of my head.

 

How would I adjust it? I took it out and cleaned it up with throttle body cleaner. Didn't replace, just out clean and in.

 

Double check the TPS was installed correctly. I don't believe the IAC is adjustable.

 

I'll take vacuum leak for $200 Alex...

 

intake manifold seated?

 

At first I was also thinking vac leak. But he still is getting the TPS high voltage CEL.

 

the throttle blade can't open itself.

 

P0123-THROTTLE POSITION SENSOR VOLTAGE HIGH
When Monitored: With the ignition on and battery voltage above 10.4 volts.
Set Condition: Throttle Position Sensor voltage at the PCM goes above 4.5 volts for 3.2
seconds.


POSSIBLE CAUSES


THROTTLE POSITION SENSOR SWEEP
INTERMITTENT CONDITION
THROTTLE POSITION SENSOR SIGNAL CIRCUIT SHORTED TO 5 VOLT SUPPLY CIRCUIT
THROTTLE POSITION SENSOR SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
THROTTLE POSITION SENSOR INTERNAL FAILURE
SENSOR GROUND CIRCUIT OPEN
THROTTLE POSITION SENSOR SIGNAL CIRCUIT OPEN
PCM


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TPS Tests:



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