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AllPar (Chrysler-Plymouth-Dodge Central)

Getting and Using Chrysler, Plymouth, and Dodge Computer Codes
Originally from the Mopar Mailing List. "From Herb with additions by Charles Hobbs." Updated / modified by Allpar.

Getting the codes

If you have fuel injection, this works on most Chrysler, Plymouth, and Dodge cars made in the 1980s and 1990s.

On newer cars (mid-to-late 1990s, 2000s):

Note: When the computer indicates major failure, it will activate Limp In mode, which guesses about data to compensate for sensor failure. This is a nice feature not used by all automakers.

If you don't find your code in this list, try clicking here for a different site's lists.

The Codes


NOTE #1.

The power module has an air-cooled resistor which senses incoming air temperature. The logic modules uses this information to control the field current in the alternator. This code applies ONLY to alternators whose voltage is computer regulated. If you lose the feed to keep RAM information stored when the engine's off, you also lose battery voltage sensing. -- Bohdan Bodnar

NOTE #2.

From the 1995 TRUCK manuals: the trailer towing package includes a transmission coolant temp sensor while the standard package doesn't. This may cause the low (no) voltage indication. -- J.E. Winburn

NOTE #3.

Matt Rowe comments: The throttle postion circuit tells the computer how far the accelerator is depressed. The Throttle Position Sensor (TPS) is on the throttle body on the opposite side of the throttle cable. The connector should have a round rubber cover over the connections. Clear the fault codes, start the car and try jiggling the wires/connectors to try to trip a fault code. Loss of this signal could cause other problems.

NOTE #4.

During cranking, the computer will test the current through the injector to see whether there's too much resistance in the injector's path. If there is, code 26 is set.

The problem may be cured with tuner cleaner on the connectors.

For TBI engines, the injector's cold resistance should be between 0.9 and 1.2 ohms (specs vary with year). This is a peak-and-hold injector. With the engine idling the peak period should be about 1.2 milliseconds whereas the hold period will vary. If it's lower than this at idle, then the injector's shorted or there's a defect in the injector driver circuit. (Bohdan Bodnar)

NOTE #5.

Wade Goldman wrote: In my case, the breather tube leading into the catalytic converter had rusted and become detached. This some how would cause the sensor to read an over rich condition and run crummy. I did not trust the reliability of the weld over a corroded surface and opted for the more expensive route of replacing the converter, breather tube and all.

NOTE #6.

The Z1 voltage is the voltage of the circuits fed by the autoshutdown relay. This typically includes fuel pump and switched-battery feed to the ignition coil(s). In my Le Baron, the Z1 circuit leaves the power module and splits into two paths: the fuel pump and the positive side of the ignition coil. Internal to the power module is the auto shutdown relay (in my case, it's a sealed box about 1" by 1"). The output voltage is monitored to determine whether the relay responds correctly. I suspect that the ASD relay (and, therefore, the Z1 circuit) also feeds the fuel injector(s) driver(s) and current sensing circuit, but can't prove this.

I've used the Z1 voltage to test for good power connections to the power module. I connected my OTC 500 multimeter from the battery's positive post to the ignition coil's switched battery terminal and measured the voltage drop using the bar graph to monitor peak voltages. Voltage spikes of around 200 mV to 300 mV are ok -- anything more means tv tuner cleaner time (or replacing the power module). Another thing to check is the maximum voltage drop during the priming pulse. With the old power module, I was losing about 2 volts across the circuit; the replacement is losing about 1/4 volt. (Thanks,


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Chrysler, Plymouth, Dodge, and Jeep car, minivan, and truck computer fault codes: how to get them and what to do with them. Good for sensor and other troubleshooting.