P1237 – FUEL PUMP SECONDARY CIRCUIT MALFUNCTIONHOW DO I REPAIR THIS PROBLEM ON

2001 Ford Focus

Tiny

cfrinwb@charter.net

February, 18, 2012 AT 5:38 PM

Car won, t start. Don't smaell gas in carb

4 Answers

Tiny

fixitmr

February, 18, 2012 AT 5:55 PM

P1237 relates to the fuel pump circuit. Check the fuse and the pump relay. If they are ok your fuelpump has probably failed.

Tiny

fixitmr

February, 18, 2012 AT 6:01 PM

Here's a more technical answer.
P1237=Fuel Pump Secondary Circuit (Fuel Pump Driver Module)

Electronic Returnless Fuel Systems (ERFS) utilize a Fuel Pump Driver Module (FPDM) to control fuel pressure. The PCM uses a Fuel Rail Pressure Sensor (FRP) for feedback. The PCM outputs a duty cycle to the FPDM to maintain the desired fuel rail pressure. During normal operation, the PCM will output a FP duty cycle from 5% to 51%. The FPDM will run the fuel pump at twice this duty cycle, e.G. If the PCM outputs a 42% duty cycle, the FPDM will run the fuel pump at 84%. If the PCM outputs a 75% duty cycle, the FPDM will turn off the fuel pump.

If the FPDM does not out any diagnostic signal, (0 or 100% duty cycle), the PCM sets a P1233 DTC. This DTC is set if the FPDM loses power. This can also occur if the Inertia Fuel Switch is tripped.

If the FPDM outputs a 25% duty cycle, it means that the fuel pump control duty cycle is out of range. This may occurs if the FPDM does not receive a valid control duty cycle signal from the PCM. The FPDM will default to 100% duty cycle on the fuel pump control output. The PCM sets a P1235 DTC.

If the FPDM outputs a 75% duty cycle, it means that the FPDM has detected an open or short on the fuel pump control circuit. The PCM sets a P1237 DTC.

Tiny

fixitmr

February, 18, 2012 AT 6:23 PM

They did also have issues that year with malfunction of FDPM. Fix is to replace it.

Tiny

Happster

August, 3, 2012 AT 5:58 PM

Great answer! What if I have both p1235 and p1237 codes? Car bucked and chugged and then stalled out. Was able to get it going with some starter fluid in the throttle body and it stayed running, but VERY rough. Also, how do I test the relay? Thanks.

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