1992 2.3 Mustang with DTC codes 542 and 543

goshogo · 10-15-2007

I just replaced the ignition and the fuel pump on my 1992 2.3. it ran well for 3 days then stopped on the hightway it has not started since i have codes 542 and 543. help please

**stlwagon** · 10-15-2007

Welcome... Let's try this forum.

b_chandler · 10-16-2007

Here's what the codes translate to:

542 (O,M) Fuel pump open, bad ground or always on - - Power / Fuel Pump Circuits 543 (O) Fuel pump monitor circuit shows no power - Power / Fuel Pump Circuits

I think I'd start at the fuel pump relay and work from there.

thico · 10-16-2007

I had the same problem with my 1995 GT V8 and it was the CCRM... (i don't know if the 1993 2.3 uses the CCRM...
What i did to solve it was take off the CCRM (constant control relay module) and changed the relay that controls the fuel pump... since i don't have this CCRM to buy here, i fix it!