U210b lost communications fuel pump control module to rcm

Hey guys I own a 2011 ford mustang. The car was previously in an accident with a locked rcm module. I got the module repaired and when it was plugged in the code says lost communication with fuel pump control module to rcm. I bought another module and it’s the same message.

I’m stumped as to what I should do.

From service info for U210B:

The fuel pump control module monitors the duty cycle and frequency of the signal it receives from the restraints control module (RCM). The fuel pump control module determines if the signal on the event notification signal (ENS) circuit from the RCM is a valid duty cycle and frequency. If the duty cycle or frequency is invalid, the fuel pump control module sends a 40% duty cycle signal on the fuel pump monitor (FPM) circuit to report the concern to the powertrain control module (PCM). The test fails when the fuel pump control module is still reporting that it is receiving an invalid duty cycle or frequency from the RCM after a calibrated amount of time.

...


The fuel pump control module monitors the ENS signal by sending a 12V low current signal on the ENS circuit to the RCM.

I grabbed that last part because that's going to be a key bit of info for your testing. Here's the relevant part of the wiring diagram:



We want to know what the voltage is on pin 19 brown/yellow of C2041A at the RCM, key on engine off, RCM disconnected. The brown/yellow circuit is the ENS circuit, which we know from the above service info should have 10V or more. This is where the U210B is coming from.

Let us know what you find on the ENS circuit, and we can figure out where to go next. Don't pull a Danner and get silly with the RCM. Keep the RCM bolted down in its home during testing.

So last night I tested the pin 19 yellow with brown. I got 10.5 volts. When I went to pin 6 at the fuel pump control module I got 5.7 volts. When I disconnected the fuel control module and retested pin 19. My volts dropped to 5.7

Ryansookwah wrote:

So last night I tested the pin 19 yellow with brown. I got 10.5 volts. When I went to pin 6 at the fuel pump control module I got 5.7 volts. When I disconnected the fuel control module and retested pin 19. My volts dropped to 5.7

During your above testing, was C2041A at the RCM connected or disconnected?

If you had 5.7V on the ENS circuit with the RCM *AND* the FPCM disconnected, then I think you've found at least one of your problems. The only variable would be if this Mustang has a 5.4L engine with two FPCM's.

They were disconnected and connected I checked the voltage both ways. I am thinking about checking the resistance of the wire.

This is a 3.7 v6. While the rcm was connected and the fpcm disconnected. At pin 6 I’d get 5.7volts. Even with it connected it was still 5.7. The only change was when the rcm was disconnected. Rcm disconnect 5 volts. Rcm connected 10 volts

You’re supposed to leave the fuel pump module connected. Unhook rcm front prove terminal and see if you get 10 volts or more

The fuel pump module sends out a bias 12 volts and the rcm is going to pull it to ground creating a duty cycle