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Pontiac Repair/shift interlock - issue shifting from park

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Question
I have 2002 Pontiac grand prix gtp 3.8 super charged 4 door. troubleshooting this issue I have not found bad/broken wires leading to the shift lock solenoid. when the key is placed just before the run position (prior to instrument cluster gauges and lights coming on) the orange/black wire, in the wiring connected to the shift lock solenoid, provides a ground to the solenoid and when brake is pressed the solenoid is released allowing it to shift from park. when the key is moved forward to the RUN position the same wire is changed to 12v positive and will not allow shift from park with brake on or off.  I believe this signal comes from the neutral safety switch (gear position switch)on the transmission.

Do you have any information on this circuit or schematic/diagram for the switch located on the transmission to help verify what signal is generated (orange/black wire) when in Park or Neutral?

I am pretty good troubleshooting electrical issues but I have not been able to find enough information on this circuit or switch to identify the problem.

Answer
Hi wayne:

I can't cut and paste diagrams into this software but your on the right path. "usually" the wires are broken right at the shifter it's self. sounds like you have that covered.
This is the best I can do and it's going to look screwed up so see what you can do with it when it prints out.. This is a 4 column trouble tree. and Like I said it looks stange the format is messed up. Sorry It's the best I can do for you.


Shift Lever Does Not Move with Brake Pedal Depressed
Shift Lever Does Not Move with Brake Pedal Depressed Step
Action
Yes
No

Schematic Reference: Shift Lock Control Schematics

DEFINITION: Transmission shift lever does not move with the ignition ON and the brake pedal depressed.

1
Did you perform the Symptoms - Automatic Transmission Shift Lock Control tests and all the necessary inspections?
Go to Step 2
Go to Symptoms - Automatic Transmission Shift Lock Control

2
 1. Turn ON the ignition, with the engine OFF.
 2. Press and hold the brake pedal.
 3. Attempt to move the shift lever out of the PARK position.
Does the shift lever move out of the PARK position?
Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems
Go to Step 3

3
 1. Turn OFF the ignition.
 2. Disconnect the automatic transmission shift lock control switch.
 3. Turn ON the ignition. with the engine OFF.
 4. Press and hold the brake pedal.
 5. Attempt to move the shift lever out of the PARK position.
Does the shift lever move out of the PARK position?
Go to Step 9
Go to Step 4

4
 1. Turn OFF the ignition.
 2. Disconnect the automatic transmission shift lock control solenoid.
 3. Turn ON the ignition. with the engine OFF.
 4. Press and hold the brake pedal.
 5. Attempt to move the shift lever out of the PARK position.
Does the shift lever move out of the PARK position?
Go to Step 12
Go to Step 5

5
 1. Turn OFF the ignition.
 2. Connect a test lamp between the off/run/crank voltage circuit of the park lock solenoid and a good ground.
 3. Turn ON the ignition , with the engine OFF.
Does the test lamp illuminate?
Go to Step 6
Go to Step 13

6
 1. Turn OFF the ignition,
 2. Disconnect the automatic transmission shift lock control solenoid assembly.
 3. Connect a test lamp between the park lock solenoid off/run/crank voltage circuit and the neutral safety switch signal circuit at the automatic transmission shift lock control assembly.
 4. Turn ON the ignition, with the engine OFF.
Does the test lamp illuminate?
Go to Step 10
Go to Step 7

7
Connect a test lamp between the neutral safety switch signal circuit at the park/neutral safety switch and battery positive voltage.

Does the test lamp illuminate?
Go to Step 14
Go to Step 8

8
Test for an open in the park/neutral safety switch ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?
Go to Step 18
Go to Step 11

9
Inspect for poor connections at the harness connector of the automatic transmission shift lock control switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?
Go to Step 18
Go to Step 15

10
Inspect for poor connections at the harness connector of the automatic transmission shift lock control solenoid assembly. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?
Go to Step 18
Go to Step 16

11
 1. Inspect for proper park/neutral safety switch adjustment. Refer to Park/Neutral Position Switch Adjustment in Automatic Transmission.
 2. Inspect for poor connections at the harness connector of the park/neutral safety switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 18
Go to Step 17

12
Repair short to battery positive voltage in the A/T shift lock control solenoid supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?
Go to Step 18


13
Repair the open in the off/run/crank voltage circuit of the park lock solenoid. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?
Go to Step 18


14
Repair the open in the neutral safety switch signal circuit of the park lock solenoid. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?
Go to Step 18


15
Replace the automatic transmission shift lock control switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes.

Did you complete the repair?
Go to Step 18


16
Replace the automatic transmission shift lock control solenoid assembly. Refer to Automatic Transmission Shift Lock Control Actuator Replacement.

Did you complete the repair?
Go to Step 18


17
Replace the park/neutral safety switch. Refer to Park/Neutral Position Switch Replacement in Automatic Transmission.

Did you complete the repair?
Go to Step 18


18
Operate the system in order to verify the repair.

Did you find and correct the condition?
System OK
Go to Step 2  

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Todd Puccio

Expertise

General auto repair,electrical issues,driveability issues,anti-lock brakes,SIR systems,HVAC,engine performance,Gm specific. I have worked at my current dealership since the 1990 model year anything much older than that I have limited exposure to. I do not have very much transmission experience so those question you may want to ask of another expert. When you send me a question let me know the exact make/model/engine and year for the car or suv you have it makes it easier to answer the questions that way. If your happy with the answer I gave you please feel free to Donate. This is a free service to you and I am not compensated at all by this web site. I have 22 years of experience to share with you and my knowledge wasn't free to me. I had to pay for my education.

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Experience in the area: I have been a technician in GM dealerships for over 22 years and I am a ASE master technician. I work at a Buick and GMC truck store Previously I worked at a Pontiac GMC store for 18 years. I Served a a lead technician when dealership was on a team system. I just recently moved to a Buick,Hummer,Saab Store when my franchise was purchased by this dealership. Organizations: ASE master technician

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Education/Credentials:High school diploma,2 year vocational school degree 2 year college degree. Associates degree in applied sciences (auto technology)Awards and Honors: GMC master technician

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Master GMC truck technician Master ASE technician in 9 categories

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