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Test Description

WARNING: This page is about a different car, the 2007 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.

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

  1. 3:  This step tests the IMS for an open ground circuit.
  2. 5:  This step tests for correct reference voltage from the TCM.
DTC P1825

Step Action Values Yes No
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle
2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
    3. IMPORTANT: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records. Using the Clear Info function erases the Freeze Frame and Failure Records from the TCM.
  3. Record the DTC Freeze Frame and Failure Records.
  4. Clear the DTC.
  5. Select IMS on the scan tool.
  6. Place the gear select lever in each transmission range: P, R, N, D4, D3, D2, and D1.
Does each range selected match the scan tool IMS display?		 - Go to Testing for Intermittent Conditions and Poor Connections Go to Step 3 
3 
  1. Select IMS A/B/C/P on the scan tool.
  2. Place the gear select lever in each transmission range: P, R, N, D4, D3, D2, and D1.
Does the IMS A/B/C/P display match the specified value for each range selected?		 HI/HI/HI/HI Go to Step 13  Go to Step 4 
4
  1. Turn OFF the ignition.
  2. Disconnect the AT inline 20-way connector. Additional DTCs may set.
  3. Turn ON the ignition, with the engine OFF.
  4. Select IMS A/B/C/P on the scan tool. Refer to Transmission Internal Mode Switch Logic
Does the scan tool IMS A/B/C/P parameter indicate HI for all range signal states?		 - Go to Step 5  Go to Step 9 
5 
  1. Turn OFF the ignition.
  2. Install the J 44152  Jumper Harness (20 pins) on the engine harness side of the AT inline 20-way connector. See Special Tools .
  3. Turn ON the ignition, with the engine OFF.
  4. Using the DMM and the J 35616  GM Terminal Test Kit, measure the voltage at terminal F of the J 44152  . See Special Tools .

    Refer to Automatic Transmission Inline 20-Way Connector End View .

  5. Measure the voltage at terminal G of the J 44152  . See Special Tools .
  6. Measure the voltage at terminal H of the J 44152  . See Special Tools .
  7. Measure the voltage at terminal J of the J 44152  . See Special Tools .
Does the voltage measure ignition voltage at all four terminals?		 - Go to Step 6  Go to Step 10 
6 Connect a fused jumper wire from terminal F of the J 44152  , signal A circuit, to ground while monitoring the scan tool IMS A/B/C/P parameter. See Special Tools .
Refer to Automatic Transmission Inline 20-Way Connector End View .
When the signal A circuit is grounded, do any other signal circuits indicate LOW?		 - Go to Step 11  Go to Step 7 
7 Connect a fused jumper wire from terminal G of the J 44152  , signal B circuit, to ground while monitoring the scan tool IMS A/B/C/P parameter. See Special Tools .
Refer to Automatic Transmission Inline 20-Way Connector End View .
When the signal B circuit is grounded, do any other signal circuits indicate LOW?		 - Go to Step 11  Go to Step 8 
8 Connect a fused jumper wire from terminal H of the J 44152  , signal C circuit, to ground while monitoring the scan tool IMS A/B/C/P parameter. See Special Tools .
Refer to Automatic Transmission Inline 20-Way Connector End View .
When the signal C circuit is grounded, do any other signal circuits indicate LOW?		 - Go to Step 11  Go to Step 12 
9 Test the signal circuits of the IMS that did not indicate HI for a short to ground between the TCM connector and the AT inline 20-way connector.
Refer to Testing for Short to Ground and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 18  Go to Step 17 
10 Test the signal circuits of the IMS that did not indicate ignition voltage for an open between the TCM connector and the AT inline 20-way connector.
Refer to Testing for Continuity and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 18  Go to Step 17 
11 Test the affected signal circuits of the IMS for a shorted together condition between the TCM connector and the AT inline 20-way connector.
Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 18  Go to Step 17 
12 Test the signal circuits of the IMS for an open or shorted condition between the AT inline 20-way connector and the IMS.
Refer to Circuit Testing .
Did you find a condition?		 - Go to Step 15  Go to Step 16 
13 Test the ground circuit of the IMS for an open between the AT inline 20-way connector and the ground distribution block.
Refer to Testing for Continuity and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 18  Go to Step 14 
14 Test the ground circuit of the IMS for an open between the AT inline 20-way connector and the IMS.
Refer to Testing for Continuity .
Did you find a condition?		 - Go to Step 15  Go to Step 16 
15
IMPORTANT: The automatic transmission wiring harness consists of 2 separate harnesses, the Automatic Transmission Wiring Harness Assembly and the Automatic Transmission Wiring Extension Harness Assembly. In order to avoid the unnecessary replacement of parts, determine which harness contains the fault and replace only that harness.
Replace the automatic transmission wiring harness.Refer to Input Speed Sensor and Wiring Harness Removal .Did you complete the replacement?		 - Go to Step 18  -
16 Replace the transmission internal mode switch.
Refer to Lower Control Valve Body Assembly Disassemble .
Did you complete the replacement?		 - Go to Step 18  -
17 Replace the TCM.
Refer to Control Module References .
Did you complete the replacement?		 - Go to Step 18  -
18 Perform the following procedure in order to verify the repair:
  1. Select DTC.
  2. Select Clear Info.
  3. Turn ON the ignition, with the engine OFF.
  4. The IMS must indicate a valid range for 4 seconds.
  5. Select Specific DTC.
  6. Enter DTC P1825.

Has the test run and passed?		 - Go to Step 19  Go to Step 2 
19 With the scan tool, observe the stored information, capture info. and DTC info.
Does the scan tool display any DTCs that you have not diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List - Vehicle System OK
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