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2009 Chevrolet 1500 5.3L Flex-Fuel: P0231 and P0693 Codes - No Fuel Pump Relay or Fuse, Truck Runs Fine

Model: 2009 chevrolet 1500 Fault Code: P0231 Posted: 2016-02-20 14:39

Hello — I'm summarizing a situation with my 2009 Chevrolet 1500 5.3L flex-fuel engine. This truck has never had any prior issues. Recently, it triggered two diagnostic trouble codes: P0231 and P0693. I replaced the battery, but the codes returned — no change. Upon checking under the hood, I found there is no fuel pump fuse or relay in place. The truck still starts and runs smoothly with no symptoms like stalling, misfiring, or loss of power. My question: What could be causing these codes? Is it possible that the Fuel Pump Control Module (FPCM) is faulty? Given that this model doesn't have a traditional fuel pump relay but instead uses an FPCM to regulate fuel pump operation, how should I proceed? Any insights or troubleshooting steps would be greatly appreciated. Thanks in advance.

Related fault codes

P0231P0693

Comments (5)

Anonymous 2016-02-20 20:23

In my vehicle, the P0693 code does not appear — this model lacks a dedicated fuel pump relay and instead uses a Fuel Pump Control Module (FPCM). The P0231 code indicates low voltage at the FPCM. After replacing the battery, did the codes persist? I recommend clearing the codes and monitoring them again. If they return, it may point to an issue with the FPCM itself.

Anonymous 2016-02-21 11:16

My mistake — I meant P0693, not P069E. I replaced the battery due to cold winter conditions. After clearing the codes, they returned. The truck starts and runs fine with no missing or stalling issues. Could a failing FPCM be the root cause? It seems like the issue is intermittent but persistent.

Anonymous 2016-02-21 13:48

How long does it take for these codes to return? Are they intermittent? I suspect a failing FPCM. If left unaddressed, this could lead to complete failure. The FPCM is located above the spare tire and requires reprogramming after replacement — not plug-and-play. To diagnose properly, you’d need a scan tool with bi-directional controls and a digital multimeter to test inputs when symptoms are present.

Anonymous 2016-02-21 14:48

Thanks for the helpful input — I now believe we're on the right track. Appreciate your insight!

Anonymous 2016-02-22 08:03

If the FPCM needs replacement, then the Vehicle Control Module (VCM) or Powertrain Control Module (PCM) will need reprogramming to maintain proper functionality after installation.