QuestionQUESTION: Hi Kevin I hope you can help. We have an 02 Town & Country Xl mini van. Two years ago the radio started acting up and would power on when it felt like it and now wont power on at all, only blinks when we push on the power button, but that is not the main reason I am writing. A couple of weeks ago the van started acting like my 72 nova did when I needed to adjust the air and fuel intake on the carburetor. When the rpm's got around 1500 it would spit and sputter and want to stall out. I took it to our mechanic who said that the cod was 107 and 108, MAP sensor voltage to high and to low. He put in a new MAP sensor and while it was hooked up to his diagnostic computer it was still giving the same 107 & 108 codes, but his computer said the map sensor was fine, so he told us that the PCM was bad. I bought a reconditioned one from a company online with a lifetime warranty. I put it in the van and it started rite up and seemed to run much better, but after we get it up to above 30 mph, it seems to bang out of gear every time the throttle is disengaged and it also jerks and bounces all over the place when the cruise control is set and it tries to coast between throttling. My nephew said that the new PCM has to get in sync with my driving and the transmission and that it would only take a little while to "break in". I called the company we bought it from and asked them about it and they said that it should not need any time to "break in" and that maybe the (BCM) blew when the (PCM) went bad and that it needs to be replaced. What can you tell me? The tranny ran smooth as glass before we put in the new (used) pcm in and now it seems to shift in and out of gear real hard. What could be the cause for this? Thanks for your time and I hope this can help someone else who might have the same problem.
ANSWER: Hi John,
I would suggest that you get a free code readout at an Autozone or similar nationwide parts store. Disconnect the battery and drive it a bit to get all the problems to display themselves. That way only 'frest' fault codes will show up. Problems like this should begin by asking the various module what they see to be wrong.
Roland
PS Sorry for the delay but I just found your question in the 'pool' to which it had been referred by the other expert.
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QUESTION: Hi Roland, I took it back to our machanic and he is puzzled because he hooked it up to his code reader thing and it still reads codes 107 and 108 (map sencer voltage too high and map sencer too low). He even took out his voltage tester and tested the wires going into the sencer. He then removed the sencer while the van was running and it stalled out as soon as he did that, so he knows that there is a vacuum like there should be. I think he said that the voltage was where it should be on start up but than stayed too high? We first replaced the map sencer and when that did'nt work we replaced the PCM and it still has'nt fixed the problem. Altho we can drive the van now because the engine only sputters and spits when the RPM's are up to 4000, which we never get it up too anyway, (unless maybe we try to pass someone while doing 60 on the interstate), as opposed to before when it would act up at only 1500 RPM. Any idea's?
AnswerHi John,
The fact that the signal voltage can be either too high or too low suggests that one or more of the three wires at the plug is shorting and opening intermittently. The signal wire, violet/brown on pin 1 goes to pin 36 at the pcm, and the ground wire, dark blue/dark green on pin 2 goes to a common ground splice where it meets grounds from several other sensors. Both those wires go thru a 10-wire black disconnect located near the spark coil pack at the rear corner of the engine closest to the driver. So check that disconnect and those wires for any sign of heat or mechanical damage. The 5 volt supply wire, pink/yellow on pin 3 of the sensor goes to a splice where it meets several other sensor wires that share that supply. The fact that no other sensors show a code suggests that if there is a problem it is between the plug and the splice which is at the same general location as the disconnect. So tracing the map harness from the plug to those two points would be desireable. From the disconnect for the signal wire (at the 10-pin's pin 2) the wire goes to the pcm. So I would suggest that an ohmmeter/continuity tester/voltmeter be applied between the plug, disconnect, pcm for the signal wire, and similarly for the ground wire. The 5 volt supply wire could be checked between the plug and the plug for any other sensor that uses that wire (such as the throttle position sensor or a/c pressure sensor). Shake the wires to try and induct a change in continuity or a short to ground or a 5 or 12v voltage source. I would suspect the signal wire is the source of the problem becauase the other two wires are shared and would likely (though not certainly) cause problem codes from the other sensors as well if involved.
Because the code persists despite the change of sensor and pcm, I have to suspect a wiring problem between those two parts.
That is how I would approach this situation.
Roland
