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Multiple Data Communication Codes (4.9L)

  1. Ensure DLC cover is properly seated to DLC connector. If it is, go to step 3). If it is not, clear all codes, install DLC cover properly and test drive vehicle for more than 10 miles. Enter self-diagnostics and recheck for trouble codes. See ENTERING SELF-DIAGNOSTICS  under SELF-DIAGNOSTICS.
  2. DLC cover contains a serial data line jumper connection. When DLC cover is in place, jumper connects DLC terminals "M" and "L" to complete the serial data line communication link between all computer systems.
  3. Ensure DLC cover is properly positioned. Enter self-diagnostics and record all trouble codes. See ENTERING SELF-DIAGNOSTICS  under SELF-DIAGNOSTICS. If both Codes I033 and I037 are set, repair open in Tan wire between DERM to IPC or between ACP to PCM. Diagnostic Energy Reserve Module (DERM) is located directly above brake pedal. DERM has Yellow connector and wiring harness. A/C Programmer (ACP) is located left of PCM, behind glove box. If both Codes I034 and I037 are set, repair open in Tan wire between IPC and PCM or between ACP and DERM. See WIRING DIAGRAMS  .
  4. If both Codes I034 and E052 are set, PCM has lost power. Diagnose as per PCM Code E052. See appropriate G - TEST W/CODES article in ENGINE PERFORMANCE. If both Codes I034 and E047 are set, IPC has lost communications with PCM. Diagnose as per IPC Code I034. If both Codes I037 and A037 are set, IPC has lost communications with ACP. Diagnose as per IPC Code I037.
  5. If Codes A037 and E047 are set (I052 may also be set), there is serial data line communication link break down. Diagnose as per IPC Code I052. If Codes I033, I034 and I037 are all set, and these are current ("C") codes, go to next step. If these are history ("H") codes, check the following and repair as needed:
    • Check for poor connections at IPC terminals C1 and C2. See Figure .
    • Check for intermittent short to ground or short to battery voltage anywhere in Tan wire circuit.
    • Check for intermittent open in Tan wire circuit between IPC and DERM, and between IPC and PCM.
    • Check each computer component along Tan wire circuit to be holding serial data line at a constant voltage.
  6. Disconnect PCM connector C2. See Figure . PCM is located on right kick panel. Remove DLC cover. Using DVOM, measure voltage at DLC terminal "M". If voltage does not fluctuate between 3 and 5 volts, go to step 11). If voltage fluctuates between 3 and 5 volts, disconnect ACP connector and reconnect PCM connector C2. ACP is located left of PCM. Using DVOM, measure voltage at DLC terminal "M".
  7. If voltage is fluctuating between 3 and 5 volts, go to step 9). If voltage is not fluctuating between 3 and 5 volts, disconnect PCM connectors. Using jumper wire, connect PCM harness connector C2, terminals A8 and A9. See Figure .
  8. Using DVOM, measure voltage at DLC terminal "M". If voltage is fluctuating between 3 and 5 volts, check PCM MEM-CAL for good connection into PCM, and check PCM connectors for good connections. If no connection problems exist, replace PCM. If voltage is not fluctuating between 3 and 5 volts at terminal "M", repair short in Tan wire circuit between ACP and PCM.
  9. If voltage is fluctuating between 3 and 5 volts, use jumper wire to connect ACP harness connector terminals C10 and C11. See Figure . Using DVOM, measure voltage at DLC terminal "M". If voltage is fluctuating between 3 and 5 volts, check for faulty ACP connections. If ACP connections are good, replace ACP.
  10. If voltage does not fluctuate between 3 and 5 volts at DLC terminal "M", disconnect Electronic Brake Control Module (EBCM) connector. EBCM is mounted to center of cross brace behind rear seat and is accessible from trunk. Using DVOM, measure voltage at DLC terminal "M". If voltage fluctuates between 3 and 5 volts, replace EBCM. If voltage does not fluctuate between 3 and 5 volts, repair short in Tan wire between ACP and DLC terminal "L".
  11. Ensure PCM connector and DLC cover are still disconnected. Disconnect Yellow DERM connector. DERM is mounted behind instrument panel above brake pedal. Using DVOM, measure voltage at DERM harness connector terminal A8. See Figure . If voltage does not fluctuate between 3 and 5 volts, go to step 13). If voltage fluctuates between 3 and 5 volts, use jumper wire to connect DERM harness connector terminals A11 and B11. Measure voltage at DLC terminal "M".
  12. If voltage fluctuates between 3 and 5 volts at DLC terminal "M", check connections at DERM terminals. If connections are good, replace DERM. If voltage does not fluctuate between 3 and 5 volts at DLC terminal "M", repair short in Tan wire circuit between DERM and DLC. See WIRING DIAGRAMS  .
  13. Turn ignition off. Disconnect IPC connectors. Leave DERM disconnected. Using DVOM, measure resistance to ground from IPC connector terminal C1. See Figure . If resistance is 2000 ohms or less, repair short in Tan wire circuit between DERM and IPC. See WIRING DIAGRAMS  .
  14. If resistance is greater than 2000 ohms, connect jumper wire from DERM connector terminal A11 to ground. See Figure . Measure resistance to ground from IPC connector terminal C1. If resistance is more than 2000 ohms, repair open in Tan wire circuit between IPC and DERM.
  15. If resistance is 2000 ohms or less, ensure PCM is still disconnected and measure resistance from ground to IPC harness connector terminal C2. If resistance is now more than 2000 ohms and terminal connections are good at IPC connectors, replace IPC. See INSTRUMENT PANEL CLUSTER  under REMOVAL & INSTALLATION.
  16. If resistance is now 2000 ohms or less, repair short in Tan wire circuit between IPC and PCM. After all repairs are completed, clear all codes and verify correct operation.
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