is there a way to test the mlps (replaced trans and now no crank)

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ID Status Date Year Make Model Transmission Type A/C Controls Public/Private
#13255 Closed 03 gmc 2500 6.0 public

replaced trans and now dash lighs up like xmas tree but no crank and mlps and new plug are rather pricey to replace if thats not the problem….is there a bypass or a test to check? thanks

Sparky

Viewing scan tool data is the easiest and I seem to remember that you have access to a scan tool. You should also be able to see the position reflected in the electronic shift indicator in the DIC.

Any codes stored?

The follow is from GM Service Information. Also see the attached diagram.

Circuit Description

The transmission range (TR) switch is part of the park/neutral position (PNP) and back-up lamp switch assembly, which is externally mounted on the transmission manual shaft. The TR switch contains four internal switches that indicate the transmission gear range selector lever position. The PCM supplies ignition voltage to each switch circuit. As the gear range selector lever is moved, the state of each switch may change, causing the circuit to open or close. An open circuit or switch indicates a high voltage signal. A closed circuit or switch indicates a low voltage signal. The PCM detects the selected gear range by deciphering the combination of the voltage signals. The PCM compares the actual voltage combination of the switch signals to a TR switch combination chart stored in memory.

Diagnostic Aids

Refer to Transmission Range Switch Logic for valid combinations of switch signal circuits A, B, C and Parity. In the Transmission Range Switch Logic table, HI indicates an ignition voltage signal and LOW indicates a zero voltage signal.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. By disconnecting the TR switch, the ground path of all TR switch circuits is removed and the PCM should recognize all circuits as open. The scan tool should display HI for all range signal states.
  1. This step tests the TR switch wiring for an open or the lack of the signal voltage from the PCM.
  1. This step tests the TR switch wiring and the PCM by providing a ground path through a fused jumper wire. When grounded, the scan tool range signal states should change to LOW.
  1. This step tests the TR switch wiring and the PCM by providing a ground path through a fused jumper wire. When grounded, the scan tool range signal states should change to LOW.
  1. This step tests the TR switch wiring and the PCM by providing a ground path through a fused jumper wire. When grounded, the scan tool range signal states should change to LOW.
  1. This step tests the TR switch wiring and the PCM by providing a ground path through a fused jumper wire. When grounded, the scan tool range signal states should change to LOW.

 

Step Action Value(s) Yes No
1
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Select TR Sw. on the scan tool.
  4. With the scan tool, observe the TR Sw. display while selecting each transmission range: P, R, N, D4, D3, D2 and D1.

Does each selected transmission range match the scan tool TR Sw. display?

 — Go to Step 2 Go to Step 3
2 Observe the IPC gear range display while selecting each transmission range: P, R, N, D4, D3, D2, D1.

Does each selected transmission range match the IPC display?

 — Go to Intermittent Conditions in Engine Controls – 6.0L Go to Step 13
3 With the scan tool, observe the TR Sw. A/B/C/P display.

Does the scan tool TR Sw. A/B/C/P parameter indicate HI for all range signal states?

 — Go to Step 15 Go to Step 4
4
  1. Turn OFF the ignition.
  2. Disconnect the TR switch 4-way connector.
  3. Turn ON the ignition, with the engine OFF.

Does the scan tool TR Sw. A/B/C/P parameter indicate HI for all range signal states?

 — Go to Step 6 Go to Step 5
5 Disconnect the IPC connector.

Refer to Instrument Cluster Replacement in Instrument Panel, Gages, and Console.

Did the affected circuit display HI?

 — Go to Step 18 Go to Step 6
6
  1. Using the DMM and the J 35616 GM-approved terminal test kit, measure the voltage from terminal A of the TR switch 4-way connector to ground.
  2. Measure the voltage from terminal B of the TR switch 4-way connector to ground.
  3. Measure the voltage from terminal C of the TR switch 4-way connector to ground.
  4. Measure the voltage from terminal D of the TR switch 4-way connector to ground.

Does the voltage measure within the specified value at all four terminals?

 10–12 V Go to Step 7 Go to Step 12
7 Connect a fused jumper wire from terminal A of the TR switch 4-way connector, signal circuit A, to ground while monitoring the scan tool TR Sw. A/B/C/P parameter.

When signal circuit A (CKT 771) is grounded, do any other signal circuits indicate LOW?

 — Go to Step 14 Go to Step 8
8 Connect a fused jumper wire from terminal D of the TR switch 4-way connector, signal circuit B, to ground while monitoring the scan tool TR Sw. A/B/C/P parameter.

When signal circuit B (CKT 772) is grounded, do any other signal circuits indicate LOW?

 — Go to Step 14 Go to Step 9
9 Connect a fused jumper wire from terminal B of the TR switch 4-way connector, signal circuit C, to ground while monitoring the scan tool TR Sw. A/B/C/P parameter.

When signal circuit C (CKT 773) is grounded, do any other signal circuits indicate LOW?

 — Go to Step 14 Go to Step 10
10 Connect a fused jumper wire from terminal C of the TR switch 4-way connector, signal circuit P, to ground while monitoring the scan tool TR Sw. A/B/C/P parameter.

When signal circuit P (CKT 776) is grounded, do any other signal circuits indicate LOW?

 — Go to Step 14 Go to Step 13
11 Test the signal circuits (CKTs 771, 772, 773 and 776) of the TR switch that did not indicate HI for a short to ground.

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

 — Go to Step 19 Go to Step 17
12 Test the signal circuits (CKTs 771, 772, 773 and 776) of the TR switch that did not indicate proper voltage for an open.

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

 — Go to Step 19 Go to Step 18
13 Test the signal circuits (CKTs 771, 772, 773 and 776) of the TR switch for an open.

Refer to Testing for Continuity and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

 — Go to Step 19 Go to Step 18
14 Test the affected signal circuits of the TR switch for a shorted together condition.

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

 — Go to Step 19 Go to Step 16
15 Test the ground circuit (CKT 451) of the TR switch for an open.

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

 — Go to Step 19 Go to Step 16
16 Replace the TR switch. The TR switch is part of the park/neutral position switch.

Refer to Park/Neutral Position Switch Replacement.

Did you complete the replacement?

 — Go to Step 19 —
17 Replace the PCM.

Refer to Powertrain Control Module Replacement in Engine Controls – 6.0L.

Did you complete the replacement?

 — Go to Step 19 —
18 Replace the IPC.

Refer to Instrument Cluster Replacement in Instrument Panel, Gages and Console.

Did you complete the replacement?

 — Go to Step 19 Go to Step 2
19
  1. Turn ON the ignition, with the engine OFF.
  2. With the scan tool, observe the TR Sw. display while selecting each transmission range: P, R, N, D4, D3, D2 and D1.

Does each selected transmission range match the scan tool TR Sw. display?

 — System OK Go to Step 2

 

 

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