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Chrysler Repair/manual valve lever position sensor:42LE transmission:


QUESTION: Should I leave the starter relay in or out when testing the LightGreen/Black wire at pin 30 of PCM to start the car.  I will use Park to see if it starts.

ANSWER: The start relay should be in its socket. You are essentially over-riding the P/N grounding switch inside the transmission by grounding pin 30, but be aware that you can then start the engine in any gear. It will test whether the starting circuit as a whole is working.

---------- FOLLOW-UP ----------

QUESTION: Hi Roland,
You were correct, as the car started normally in park after the pin into  Ltgrn/Bl wire-grounded at the PCM.  While I was at the PCM I again checked the Ltgrn wire at the plug and also the connection at the starter relay Pin C and they looked good and were tight.  I also rechecked the brown/yellow at pin 41 of the TCM plug and didn't find any problem with the wire.
As you said, the authorization to close the starter relay is provided by the p/n switch inside the transmission which when in the p/n positions grounds the brown/yellow wire and the black/light green wire, both side-by-side at one end of the 10-pin plug of the trans. If I use a multimeter across the pins on the PRNDL switch that correspond with the plug wiring for the brown/yellow wire and the black/light green wires I assume I should I be checking resistance, and if so what sort of reading should I get.  
Next, when checking the plug other than cleaning the sockets with electrical cleaner and looking for a broken wire is there any thing else to check for or use of the multimeter on the plug with different switch positions? Thanks many fold for your help.

Hi Bob,
To check the position sensor switch (with the plug removed, and going around its pins as identified by the color of the wire on the plug)
black/light green grounded in P and N
brown/yellow          same
violet/white         "         PRNL
violet          "          P3L
light green/black    "         NOL
violet/black is connected to white when in R
All other positions of the switch should read infinite ohms
connected to ground means 0 ohms between the pin and the - post clamp of the battery
connected pins means 0 ohms between the pins

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Roland Finston


Free fast answer to your repair question about a Chrysler/Dodge/Plymouth car, minivan, SUV, or truck. Problems with electronically controlled engines and transmissions as well as body wiring problems are my specialty. This free troubleshoot advice forum helps you diagnose faults, minimize repair costs or do-it-yourself.

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Yahoo Autos Group called The Chrysler Lebaron Club (co-moderator)

Advanced degrees in Physics/bruised knuckles

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