at the signal line is shorted to the supply line.

Question

P0123 - Got this code right after washing the engine bay of my 1999 Jeep Grand Cherokee Laredo 4.0 Liter. Checked with multimeter for the situation of each contacts on the connector (harness side) for the TPS when the ignition key is at "ON" position. The black wire (ground) is the signal wire (middle one) has 5.18 V as does same the supply (third one). So, it's clear that the signal line is shorted to the dupply line. TPS seems good I guess. Therefore, what can I do to resolve the problem? Thanks.

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Answer 1

P0123 TPS (throttle position sensor ) circuit high input

With the TPS disconnected ,the signal circuit should measure 5.5volts,,the black wire should be 0 volts,The signal wire connected to the TPS (key on engine off) should be 0.26 volts, (with minimum throttle opening) at maximum throttle opening you should measure 4.49 volts.P0123 can also be when the TPS signal is not smooth.clean and dry connection is critical

Comments

Thanks Reynaldo. I knew the proper circuit conditions should be as you said. Read it from one other source. By the way, my posting lacked some more detailing

>> I actually put the ignition key at "ON" position without of course the engine running.

>> The ground line is 0 Volt.

>> The supply line is 5.18 Volt.

>> The signal line is 5.18 Volt as well.

So, this shows that the signal line shorted to the supply line somewhere, caused by my washing of the engine bay. Water and/or grease or the water pressure when washing has made the two lines to short/connect and the challenge is to trace that point. I looked at the TPS connector and it seemed fine but still blew some air pressure and sprayed some QD dielectric electronic cleaner to break off the shorting but no results. I did several code clearing with scanner and car battery unhooking but the P0123 code keeps on coming back (instantly). I've to mention that prior to this P0123 code, I was gettong two others. One was low volt input when it was expected some because of other inputs like vacuum pressure and RPM (when I am in fact driving at speed - like 50-60 mph). The other second code was something like the TPS having "performance" issues. However, after some 20 miles of driving those two codes are not coming back. Also, jumping rpm readings at idle, rough idling, sputtering, hesitation gradually disappeared. I got the engine cutting off at idle a couple of times. So, these two codes going away along with the symptoms probably mean that the water that has gotten into somewhere shorting the lines is drying out and hopefully within a few days my Jeep is going to running normal again.

Therefore, I guess it's a good idea if I wait in hopes of this or, I appreciate it if I am helped where to look for to find the problem and resolve. Thanks guys.