Rob98cherokee

hey guys

the jeep's been hating the rain lately.. stalling shuddering, erratic behaviour.
finally started throwing some codes, first ignition coil primary/secondary. A, B, C. cleared.. ran.. didnt come back.

hosed down the engine bay, in the rain... TPS codes...

P0123 switch circut High input.

found a wiring diagram from google.. http://ww2.justanswer.com/uploads/br...5_130136_4.gif

followed center pin to the ECM A23 for TPS return. .4 ohms. Good wire. but i have Voltage KoEo. Cool wire shorted to power, pull apart the ecm connector and snip it. The ECM is sending power OUT on #23.. doesnt sound right.. clean all grounds, use 2 gauge jumpers all around.. good good grounds.. Ecm sending power OUT.. try my backup ECM.. Same thing.

? im freekin getting confused. everything Ohming out OK. and if i take the #23 wire and put it to ground, input High turns into Input LOW

HELP pleasee

Rob98cherokee

have been working on this most of the day.. Autoenginuity is showing me that the absolute throttle position is blinking.. blinking....
7%... 72%... 0%... alternating but blinking not steady.
still have too much voltage on the #23 wire with an additional ground spliced into the circuit ground side just to be sure.

still reading 3.75V unloaded when at 0% throttle actual. and 4.75V wide open. and 5.13V unloaded comming out of the ECM @ TPS signal.

Bularf

SYMPTOM
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
- TPS voltage change not smooth
- TPS harness/connectors intermittent problem (D)
- TPS harness/connectors intermittent problem (C)
- TPS harness/connectors observable problem
- Throttle position sensor ground circuit open
- TPS signal or S/C switch signal circuit shorted to voltage
- Throttle position sensor signal circuit open
- TPS signal circuit shorted to 5-volt supply circuit
- TPS (voltage < 1.0 volt)
- Powertrain control module

Rob98cherokee

PCM and what i call the ECM same thing on these? the computer under the hood, drivers side next to air cleaner.. 3 connectors, black, gray, white..??

because i have tryed the spare computer i have and it still puts power (volts no amps) out @ pin 23.

5Volt supply and amperage OK. Lights 12v incandescent test light. ground ok also ohms good and lights test light.

Bularf

Im really not sure without havin my hands on the jeep. That is from the web site I use to read codes and thought it might be helpful

Rob98cherokee

Fixed.

running 2nd 4 gauge wire to block.(origional measured 3ohms, but under load up to 40) to neg. battery. running 10 gauge from neg battery to ECM up by the air filter grounds that come out of the harness to the body.(maintains 10ohms loaded). ECM output voltage on TPS inlet #23 went down to 3 volts. still not enough amps to do anything.

p0123 came back.. went away... came back.. replaced the TPS with a cheepie from autozone.. went away.. 20 mile test run.. doing ok. ill let it cool off.. and hit it with the garden hose to represent running in the rain.

jmlight10

Did cleaning up the grounds solve the issue, long term? I have the same problem - 4.6 volts coming out of A23 at the PCM.

lawsoncl

Measuring the signal wire disconnected from the TPS is pointless, because the input is floating. It's normal to see it floating with 4+ volts when disconnected. What does it read with it plugged into the TPS? You verified good ground and good 5v at the sensor?

jmlight10

Yeah, reads good. Ground is solid and measurements don't change from PCM, TCM, Chassis, and Battery ground. 5.15 volts at the sensor. Just chasing an intermittent problem, and it is very hard to replicate but leaves me stranded for a little bit on the road until it decides to fire up again. Any other ideas for the p0700/p0122/p0123 combo? I appreciate the help.

Rob98cherokee

replace the tps sensor. But check your ground.

this was around 10 years ago, the problem never returned.

GzrGldr

I have the same issue after pressure washing my undercarriage after a 4 wheeling trip. It'll start, drive for a little bit, then stumble for a bit, then stall. After letting it sit for a while, it will fire back up and be fine. I don't throw any codes though, so have never been able to figure it out. It is definitely something that is getting wet and shorting out, but darned if I can find what it is. I have resigned myself to only washing it in my driveway where I don't have to worry about it. I thought it might be the CPS, but can't find an OEM replacement.