Jeep cherokee misfire

Hi all, I have a 98 xj with a 6 cyl 4.0 that reads .045 volts at the unplugged TPS harness pigtail from the two outermost connectors, these are supposed to be 5vdc, and get an ignition misfire code, a p0622 generator f field, a low TPS sensor input voltage, and something about trans control out or something, could this be the PCM, I've heard of possible shorts, alternator? It still read the exact same voltages with the jeep on/off with a battery charger on/off, any suggestions, I am good with electricity, but this is completely blowing me away.

Properly test the TPS. Consult the Jeep Factory Service Manual if necessary. If the TPS is out of specification, replace it with a genuine Jeep TPS.

The TPS has direct input to the Transmission Control Unit (TCU), and is likely the cause of the other fault codes. If you don't have 5 volts supply and good continuity to ground, suspect wire harness issues like short circuits or open circuits.

The PCM supplies approximately 5 volts to the TPS. The TPS output voltage (input signal to the PCM) represents the throttle blade position. The PCM receives an input signal voltage from the TPS. It is best to use an analog meter (not digital) to see if the transition from idle to WOT is smooth with no dead spots. With your meter set for volts, put the black probe on a good ground like your negative battery terminal. With the key on, engine not running, test with the red probe of your meter (install a paper clip into the back of the plug of the TPS) to see which wire has the 5volts. This will vary in an approximate range of from .25 volts at minimum throttle opening (idle), to 4.8 volts at WOT wide open throttle.

Not really sure about the 98 but the 97 has a brown and yellow wire which is the sensor ground, I'd ohm test this ground.

The orange wire is usually the 5 volt sensor supply, I usually start out by testing this to chassis or battery ground.

Multiple sensors use the same 5 volt supply, sync sensor, MAP, CPS and TPS. Check the orange wire at another sensor, just to see if you possibly have a bad splice. Unplug all the orange wire sensors and see if the full 5 volts come back. Sometimes the 5 volt supply crashes with a shorted or partially shorted sensor and may return when the bad sensor is unplugged.

The sensors sharing the same 5 volt supply changes some year to year, I listed the 97 shared 5 volt sensors, it may be different for the 98.

The TPS has been replaced and before and after voltages stay the same on ground of battery and middle pin, goes from .04 to .043vdc.

Measure between pin 3 (orange wire) at the TPS and ground to see if you have 5 VDC. If you do, then the ground return is bad. Both 5 VDC and the ground come from the PCM. Both of the wires have at least one splice between them and the PCM. You can check the voltage at the PCM too. Connector C1 pin A17 is the 5 VDC and pin A4 on the same connector is the sensor ground.

No, at the harness connector for the TPS it measures about .043-.045vdc, it also has what seems like a misfire, have tested injectors ohms and they check out, also individually unplugged them while running, and they all worsen the idle, while running the misfire will shake the whole jeep, have to check it out on Monday with all your suggestions, at the lake house for the weekend now.

How do I check other sensors are there areas that are common problems areas for shorts or open circuits, and am I better off searching through the harness for problems or buying a pcm from a junkyard.

Sorry, not the middle pin on post 4 the orange wire or hot pin

Ok guys, unplugged ect, map, iat, TPS, and the vacuum sensor by the TPS, and re plugged them all in, and the 5 volts came back to all with 5 volt reference power, but it still stumbles, my TPS is at 1.03vdc signal(middle wire) at idle, closed position, and 4.16 at WOT, now the battery keeps dying with the jeep shut off after the jeep sits for 5 minutes, no lights on, exterior or interior, but I can shut it off and restart it instantly just fine, but cannot do anything tonight, as I ripped the plug wire off of the plug cap terminal, this jeep has had the cap and rotor replaced about a week ago, when we went up to the upper peninsula, before the symptoms appeared.

Dekamdylan said:

.....now the battery keeps dying with the jeep shut off after the jeep sits for 5 minutes.....

Click to expand...

That is a very high discharge rate, and dangerous in that
it can start a fire. Check the positive battery cable and
starter circuit for a short circuit. The source of the short
will be very hot, so feel around at the cable and starter.
Also the starter solenoid.

Ok, thanks, I checked it with a multimeter and it read 0.0vdc after 25 minutes

Replaced mud filled alt. and all symptoms were cleared