Diagnostic Information for MIL Illuminated with DTC P1825 or P1915 Found Current or as History Code in TCM, No PRNDL Display, Potential No Engine Crank

The following diagnostic information will aid the technician if the MIL is illuminated with DTC P1825 or P1915 found current or as a history code in the TCM along with a no PRNDL display and the potential for no engine crank.

1. Use the Tech 2® to capture and record Freeze Frame/Failure Data for all DTCs set. Review the data to determine:

•	Vehicle speed, commanded gear, transmission temperature, throttle position when DTC set (use to attempt to duplicate failure)

•	IMS A/B/C/P and IMS state

2. Using the Tech 2®, navigate to transmission data and scroll down to IMS. With the ignition ON and the engine OFF, observe the IMS A/B/C/P switch states and IMS states for each shift lever detent position. The chart following this list shows the correct states.
3. If all IMS readings are normal, monitor the PNP status in the engine data list during DTC setting to isolate a possible open or short to ground on the dedicated PNP signal between the TEHCM and the ECM.
4. If all IMS and PNP readings are normal, the condition is intermittent in nature and determination of the defective component will be made based on freeze frame data and previous repair history or warranty data. Proceed to History DTC below. If the readings are not as specified above, the fault is still active. Proceed to the Active DTC section below to determine which component(s) is defective.

HISTORY DTC

If all readings are normal per Step 2 above, capture and record Freeze Frame/Failure Data, clear DTCs and attempt to duplicate the fail conditions.

1. If the DTC does not reset and the original freeze frame data reports an IMS A/B/C/P code of "HLLL" and the IMS state of "Neutral/Drive 6", complete the following:

Important: Typical Freeze Frame operating conditions: ISS >500 RPM, OSS =0 RPM or low value, Engine Torque >30 N·m.

Important: There is no calibration update for vehicles equipped with a 6L90 RPO MYD transmission or 2008 model year vehicles. These calibrations were updated before production began.

•	Update the TCM calibration file to the latest released on TIS2WEB.

•	Inspect the shift cable for incorrect routing, kinks, severe bends and/or a damaged or twisted rubber boot at the transmission end of the cable.

•	Check and ensure proper cable adjustment.

•	Determine if the shift lever can be hung-up between Neutral and Drive 6. If so, there may be excessive drag in the system.

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Move the shift lever through each detent position, ensuring positive detent feel. If any concern is noted, remove the transmission oil pan and repeat the shift lever movement. Ensure that the detent spring roller moves to the bottom of the valley on the detent plate for each shift lever position. Inspect the detent spring roller and ensure it is centered on the detent plate. The spring arms should not be rubbing on either the IMS arm or detent plate.

2. If the DTC does not reset and original freeze frame data reports an IMS A/B/C/P code of "HHLH" and IMS state of "Blank", complete the following:

Important: Typical Freeze Frame operating conditions: ISS >500 RPM, OSS >0 RPM, Vehicle Speed >0 MPH

•	Replace the Internal Mode Switch (IMS) if the Vehicle Build Date is prior to March 31, 2007. If not, continue with this bulletin.

Important: There is no calibration update for vehicles equipped with a 6L90 RPO MYD transmission or 2008 model year vehicles. These calibrations were updated before production began.

•	Update the TCM calibration file to the latest released on TIS2WEB.

3. If the DTC does not reset and original freeze frame data reports an IMS A/B/C/P code of "HHHL" and IMS state of "Invalid", complete the following:

Important: Typical Freeze Frame operating conditions: ISS >500 RPM, OSS =0 RPM, Vehicle Speed >0 MPH

•	Replace the Internal Mode Switch (IMS) if the Vehicle Build Date is prior to March 31, 2007. If not, continue with this bulletin.

Important: There is no calibration update for vehicles equipped with a 6L90 RPO MYD transmission or 2008 model year vehicles. These calibrations were updated before production began.

•	Update the TCM calibration file to the latest released on TIS2WEB.

4. If the DTC does not reset and original freeze frame data reports an IMS A/B/C/P code of LLLH, LLHL, LHLL or PNP Switch is P/N in all gears, failure is a short to ground condition and is most likely in the Control Solenoid (with body and TCM) Valve Assembly (TEHCM), complete the following:

•	Replace the TEHCM (TCM). If the Vehicle Build Date is prior to March 31, 2007, also replace the IMS.

Important: There is no calibration update for vehicles equipped with a 6L90 RPO MYD transmission or 2008 model year vehicles. These calibrations were updated before production began.

•	Update the TCM calibration file to the latest released on TIS2WEB.

ACTIVE DTC/FAULT ACTIVE

If the fault is still active per Step 2 above, or after a test drive, continue with component tests defined below:

1. Ensure proper system performance:

•	Inspect the shift cable for incorrect routing, kinks, severe bends and/or a damaged or twisted rubber boot at the transmission end of the cable.

•	Check and ensure proper cable adjustment.

•

Remove the transmission oil pan and repeat the shift lever movement, ensuring that the detent spring roller moves to the bottom of the valley on the detent plate for each shift lever position. Inspect the detent spring roller and ensure it is centered on the detent plate. The spring arms should not be rubbing on either the IMS arm or detent plate.

2. Disconnect the IMS connector at the Control Solenoid (w/body and TCM) Valve Assembly (TEHCM). With the Tech 2® connected and the ignition ON and engine OFF, the Tech 2® should report all IMS states A/B/C/P as high (H) and the PNP Switch should display "In Gear".

•	If any of the A/B/C/P circuits displays low (L), the TEHCM is faulty and should be replaced. If the Vehicle Build Date is prior to March 31, 2007, also replace the IMS.

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If the PNP Switch Circuit (Tech 2® Engine data) displays "Park/Neutral", a short exists in the TEHCM or the wiring connecting it to the ECM. Disconnect the transmission pass-through connector. Check for continuity between the pass-through P/N Signal pin 3 (refer to Automatic Transmission Inline 16-Way Connector End View in SI) and the valve body assembly. If continuity exists, a short to ground is present in the TEHCM and it should be replaced. If the Vehicle Build Date is prior to March 31, 2007, also replace the IMS. If there is no continuity, the problem is outside the transmission.

Important: The bad bit should be consistent with the bad bit identified in Step 2.

3. Connect a 3-amp fused jumper wire between the common pin (Pin A) and pins B, C, D & F in the TEHCM IMS connector (refer to Automatic Transmission Internal Connector End Views in SI). As each circuit (B, C, D & F) is grounded with ignition ON, engine OFF, the Tech 2® should display low (L) for the IMS bit.

•	If any of the A/B/C/P circuits displays high (H) when grounded, the TEHCM is faulty and should be replaced. If the Vehicle Build Date is prior to March 31, 2007, also replace the IMS.

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If Pin F in the PNP Switch Circuit (Tech 2® Engine data) displays "In Gear" when grounded, an open exist in the TEHCM or the wiring connecting it to the ECM. Disconnect the transmission pass-through connector. Check for continuity between the pass-through P/N Signal Pin 3 (refer to Automatic Transmission Inline 16-Way Connector End View in SI) and TEHCM IMS connection Pin F (refer to Automatic Transmission Internal Connector End Views in SI). If there is continuity, the problem is outside the transmission. If there is no continuity, replace the TEHCM. If the Vehicle Build Date is prior to March 31, 2007, also replace the IMS.

Important: The bad bit should be consistent with the bad bit identified in Step 2.

4. If the two tests above indicate correct TEHCM operation and the condition still exists, the IMS is faulty and should be replaced.

Important: There is no calibration update for vehicles equipped with a 6L90 RPO MYD transmission or 2008 model year vehicles. These calibrations were updated before production began.

5. Update the TCM calibration file to the latest released on TIS2WEB.