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Wiring harness problem? (Not on my Chevelle.)

1289 Views 6 Replies 4 Participants Last post by  chevguy
First off, I’m sorry to have to post a non-Chevelle question here but I’m out of other options. I have a 97 Dodge Avenger that is throwing a misfire code. I’ve changed the plugs, wires, cap, rotor, and the Intake Air Temperature sensor. When none of those resolved my problem I ran some tests on the MAP sensor. I followed the instructions in my Chilton book to do them. The instructions are as follows:

On the Sensor Connector
Terminal 1 is the 5-volt power supply
Terminal 2 is the Sensor Ground
Terminal 3 is the Map Sensor Signal

On the PCM plug
Terminal 36 is the MAP Sensor signal
Terminal 43 is the sensor ground
Terminal 61 is the 5-Volt power supply

1. check connector, etc.

2. Test the MAP sensor output voltage at the sensor connector between terminals 1 and 3.

3. With the ignition switch ON and the engine not running, the output voltage should be 4-5 volts. The voltage should fall to 1.5 - 2.1 volts with a hot, neutral idle speed condition. If OK, go to step 4 or 5. If not OK, go to Step 6 or 7.
when I tested the connector, my voltmeter read zero. When I dropped the meter down to the lower range (2V), my output is about .003

6. Test the MAP sensor ground circuit at the sensor connector terminal 1 and PCM terminal 43. If OK, go to Step 8. If not OK, repair as necessary.
this test comes out fine

7. This test is for a 95 only.

8. Test the MAP sensor supply voltage between the sensor connector terminals 2 and 1 with the ignition key in the ON position. The voltage should be about 4.5 - 5.5 volts.
This tests out fine

9. There should also be 4.5 - 5.5 volts at terminal 61 of the PCM.
This tests out fine

10. This test is for a 95 only.

11. If not, repair or replace the wire harness as required.

So as far as I can tell, the only problem that I found was a problem way up at step 3. Now, if my understanding is correct, the meter should be testing the circuit completeness between the supply and the signal on the PCM side. However, this still doesn’t make perfect sense to me how this can be a complete circuit. So, does this sound like a wiring problem? If so, how can this be fixed? Do I need to replace the entire harness? Any other suggestions?

Thanks for any help that you may be able to provide.
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Chev,
Before you spend a lot of time on the electronics, I would do a quick compression test to make sure that something is not mechanically wrong. It does not take much difference in cylinder pressures to cause the pcm to sense what it thinks is a missfire. A sticking valve can do it and is very common.
Hope this helps,
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