help with codes

[rsliman]

I think i may have done some serious damage to the old heap 98 xj 4.0 auto... I found some mud and puddles and spent some there repainting the jeep a brown color. But now my check engine light is on and it shifts weird... or sometimes not at all... i took it to autozone and it flashed these codes

po121 - Throttle position sensor and MAP sensor disagree with each other

po123 - Throttle position sensor voltage high

po700 - The automatic transmission computer or Aisin computer has a problem

on top of all this i think i fried my alternator.... could it be just water in the sensors.. (i hope).. or does this sound like a more serious problem.

thanks for any help

[anony91xj]

Have the alternator tested at AutoZone as well. The alternator in the XJ's is mounted really low where it's succeptable to water, some genius designed that. Anyway, I've blown quite a few XJ alternators in the mud/water because it's mounted so low. If yours is bad, get one of AutoZone's Lifetime Warranty ones. It'll cost a bit more, but that's OK because they'll warranty it if you ever sink it again (I bet you will too) :D .

Also, it sounds like your Throttle Position Sensor has gone bad. Be it from taking on water or just wearing out, who knows. But that sensor does contribute to calculating shift points and such, so it could be your problem. It could also account for the P0700 code (which should be "TCM Malfunction" or similar)..since the TPS is a vital sensor to the transmission control module. Get the specs from the FSM and ohm it out, go through the diagnostic procedures for P0121 and P0123, you'll probably find a bad TPS...but it's always good to go through the diagnostic before just throwing a sensor in there.

Just FYI, P0121 isn't called "TPS and MAP disagree". The proper definition is " Throttle/Petal Position Sensor/Switch A Circuit Range/Performance Problem "

[vajeeper]

sorry dont mean to jack your thread but how do you find out error codes?