DTCs Set Due to Transmission Fluid Pump Fuse

automatic transmission (RPO MRG) may have an illuminated Check Engine MIL and/or the engine stop/start feature may be inoperative. DTC P2796 (Auxiliary Transmission Fluid Pump Control Circuit) and DTC P2798 (Auxiliary Transmission Fluid Pump Relay Control Circuit Low Voltage) may be set in the Transmission Control Module (TCM).

During diagnosis, 0 (zero) volts may be measured at the auxiliary fluid pump. In addition, fuse 92 (F92UA) may not be found in the UBEC. (Fig. 16)

 

Fig. 16

 

Some Malibu models may still have the fluid auxiliary pump powered by fuse 12, G5 Transmission Fluid Pump (Electric/Auxiliary, MRG, F12DA). This fuse may be missing or open, and the fuse box label may read “Not Used.”

If the fuse is missing from the UBEC, look for fuse 12 (F12DA) in the instrument panel fuse block to be either open and/or missing. If the fuse is missing from the instrument panel fuse block, a 20 Amp fuse should be installed into the fuse 12 (F12DA) location. (Fig. 17)

 

Fig. 17

 

With the fuse installed, check for voltage at the pump. If voltage is present, the vehicle should be driven to verify the DTCs do not reset and that the engine stop/start system operates properly.

If the DTCs reset, follow the appropropriate diagnostics in the Service Information for the 2019 model year.

 

– Thanks to Bill Alley

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