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2002 Jeep Grand Cherokee WJ 4.7L HO PCM Replacement Causes P0130, P0136, P0152 and P1491 Aftermath

Model: 2002 WJ Jeep Grand Cherokee Overland Fault Code: P0130 Posted: 2017-05-11 14:20

Hello, I own a 2002 Jeep Grand Cherokee WJ 4.7L HO with 98,500 miles. The vehicle was running fine until one day it stalled while parked in the driveway. When I tried to restart it, the engine cranked but wouldn't start. At that moment, the fuel gauge dropped to zero, the battery gauge reached minimum, and both the SKIS indicator lamp (solid) and the Malfunction Indicator Lamp (MIL — equivalent to the Check Engine Light) illuminated. I first attempted to retrieve OBD II codes using the vehicle's built-in system by performing a key-on-key-off cycle three times. No codes appeared. I then used an inexpensive OBD II scanner, which also failed to detect any active or stored codes. After extensive research and assistance from a friend’s MaxiSys Autel MS906 scanner, I was able to access stored digital trouble codes (DTCs) directly from the SKIM module. The presence of a 'PCM Status Failure' DTC indicated that the Powertrain Control Module (PCM) was failing — despite appearing undamaged externally. While external corrosion is commonly cited as a cause of PCM failure, this unit failed after just 98,500 miles, suggesting potential design flaws in the original 2002 WJ 4.7L HO model. I replaced the PCM with a refurbished unit from All Computer Resources. After installation, the fuel and battery gauges returned to normal, and the SKIS indicator lamp turned off. However, the MIL remained on. The engine started successfully but exhibited rough idle during warm-up. I cleared all stored codes using the Autel MS906 scanner and restarted the vehicle. A few minutes later, the MIL reactivated, and the following diagnostic trouble codes appeared: - P0130: 1/1 Oxygen Sensor Heater Circuit Malfunction - P0136: 1/2 Oxygen Sensor Heater Circuit Malfunction - P0152: 2/1 Oxygen Sensor Shorted to Voltage - P1491: Rad Fan Control Relay Circuit Given that the vehicle was performing normally prior to the PCM replacement, I believe these new codes are likely related to a programming or compatibility issue post-installation. While some users have reported similar symptoms after PCM swaps, none have shared a successful resolution method. I contacted All Computer Resources and they recommended performing a 'hard PCM reset' — disconnecting the negative battery terminal, removing the PCM wiring harness, allowing it to sit for one hour, then reconnecting everything. I am skeptical this will resolve the issue but will perform it as advised and report back with results. Additional note: The 'PCM Status Failure' DTC is not an OBD II-compliant P-code. It is a module-specific fault stored in non-OBD II systems (such as those found on the WJ), accessible only via specialized tools like a DRB III or Autel MaxiSys MS906. For reference, here is a list of electronic modules available on the 2002 WJ: http://www.wjjeeps.com/modules.htm

Related fault codes
P0130P0136P0152P1491
Comments (4)
Anonymous 2017-05-11 15:04

Try their suggested hard reset — it might be a verification test outlined in the Jeep service manual. I’ll check that if time permits, but note that the PCM was disconnected from power during shipping and installation. Some key questions: - What was the exact code for 'PCM Status Failure'? - With the key off engine (KOEO), check the voltages of the three oxygen sensors — could they be reading abnormally high now?

Anonymous 2017-05-11 16:56

I’m concerned that these codes may not trigger the MIL to illuminate and might instead point to a deeper PCM or sensor issue. It’s important to verify whether these codes are actually valid before assuming a hardware failure. Note: I believe these specific codes would typically not cause the MIL to come on, but this should be double-checked with actual diagnostics.

Anonymous 2017-05-12 09:14

kev2 wrote: Try their suggested hard reset — it might be a verification test outlined in the Jeep service manual. I’ll check that if time permits, but note that the PCM was disconnected from power during shipping and installation. Some key questions: - What was the exact code for 'PCM Status Failure'? - With the key off engine (KOEO), check the voltages of the three oxygen sensors — could they be reading abnormally high now? Quick update: The hard reset did not resolve the issue. The same codes reappeared after restart. I’ve contacted All Computer Resources again, and they are shipping a second refurbished PCM unit. It should arrive in 7 to 10 business days. I’ll provide an update if this new unit resolves the problem. Clarification: 'PCM Status Failure' is not an OBD II-compliant P-code. It’s a module-specific fault stored within non-OBD II systems (such as those on the WJ), accessible only via tools like DRB III or Autel MaxiSys MS906. For reference, see this list of available electronic modules on the 2002 WJ: http://www.wjjeeps.com/modules.htm

Anonymous 2017-05-12 10:30

As a precaution, before removing the current PCM, I recommend checking oxygen sensor voltages with a scanner — if they didn’t clear earlier, could these codes be accurate? Could there be a wiring issue? Still unsure what exactly happened to the original PCM.