Ultimately, today, our 1997 Cherokee Sport (4.0L) would barely start... and would die if you let off the gas and tried to let it idle. Checked codes -- OBD Code #25 - Automatic Idle Speed Motor circuit fault...

Backstory:
1] Bearings on water pump went out. Replaced water pump, thermostat and lower radiator hose.
2] Have had air bubbles in cooling system... so when air trapped at t-stat, the Temp gauge has read just over 100 deg. F. This triggers the CHECK ENGINE light. (I have burped the line but process has been taking days to get all out...).
3] As a result, Jeep has been run quite a bit around town with Check Engine light on (driveability seems to go out the window)
4] Seems that running with Check Engine light may have caused the Code #25, since Code #25 has never happened before, and seems awful weird that it would be a totally new problem. Input? Thank you.

 

The CEL did not cause code #25. Code #25 caused the CEL. There was a disagreement between the PCM and the IAC, or the wiring in between that caused it. Resulting in code #25. It never happened before. Is that wierd? No. Parts can fail at anytime for any reason.

How does that trigger the CEL? You just said code #25. Code #25 is for the IAC, not the temperature gauge.

Im confused.

 

How does that trigger the CEL? You just said code #25. Code #25 is for the IAC, not the temperature gauge.

Im confused.[/QUOTE]

No, You are right, when the Temp Gauge reads low it puts out Code #22 - "Engine coolant temperature sensor above or below acceptable voltage" Code #22 is the code that has been triggering the CEL repeatedly over the last week. BUT... in the current condition... it is now Code #25 (and the problem I described).

Do you have (or could you reference) a protocol to problem solve the Code #25? Thank you.

 

Try this for code #25:
http://cruiser54.com/?p=60

For code #22 remove the CTS (coolant temp sensor) and polish the end with a 3M pad or 0000 steel wool.

If neither works you may need to replace the units.