My son wrecked a 2003 ram with 3.7 auto, I found a 2002 ram so I put the engine and tranny along with the wiring harness under the hood and to the rear of the truck. Now I get code 1388 (asd) which shuts the power off to the fuel pump. I have tried both computers with same results. I have cleared the codes but asd stays I have swapped the regulator and tried jumping regulator 30 to 87 still no fuel power. I didn't change the wiring to the cab. Ii have run jump power to the fuel pump and the truck will run that way. Anybody got any ideas?

 

It's saying The PCM is trying to turn the ASD Relay on, but can't see it.


Be sure the relay socket is good. Pin 86 is the 12 Volt side of the relay coil, and pin 85 is the side that is grounded by the PCM. You're saying that it works if you bypass the relay, but not if you swap it with another one?

Does '03 have PDC OR TIPM?

Bedtime now, I'll check on you in a few hours.

 

"You're saying that it works if you bypass the relay" I bypassed the relay ( pin 30 to 87) still would not work. The pump would run if I ran a new ground straight to frame bypassing the PCM, which would leave the pump running anytime the key was on engine running or not. By the wiring diagram the pump grounds thru the PCM. it has a pdc. I have 2 of everything and have swap the pdc and the Pcm with the same results Thanks

 

I don't have an '03 manual, but according to my '01, the ASD and Fuel Pump relays are not the same.


The ASD Relay provides power (12 Volts) to the Ignition Coil, Fuel Injectors, O2 Sensors, and PCM (OK, I'm awake!)


The Fuel Pump Relay only provides power (12 Volts) to the Fuel Pump.


The ASD Relay gets it's power from fuse F6, 30 amp, in the PDC.
for '03, it's F2, 30 amp.

The FP Relay gets it's power from fuse F3, 20 amp, in the PDC.
For '03, it's F17, 15 amp.


Where in the drawing are you placing the ground?


I'll look for an '03 manual also.
Looking at an '03 manual online now.

 

The PCM runs the ground for the fuel pump, I am assuming the asd code has the pcm shut the fuel off. If I bypass the PCM and use a fixed ground the pump will run anytime the key is on motor running or not, I would not be comfortable with that. I have check power at both relays, working replaced both no change replaced both fuses no change.

 

In the service manual it shows the pcm controlling the ground wire from the pump

 

Have to find another one. Was viewing manual, and it died and went back to 1st page. could only view 1 page, no search function. Download was bloated with adware and at least 1 virus.

 

I am seeing engine dependent options in the diagrams that change the connections between the relays and the PCM. Is the replacement engine and wire harness identical to the original


I'm starting to think that if the harness is different, the PCM and ASD relay can't communicate, and I believe, this is why you got the ASD Relay error P1388 (or was it P1389?).


The Fuel Pump Relay gets it's power (12 Volts) on pin 85 from the Ignition Switch(RUN) and is switched on by the PCM Connector 3 Pin 19 providing ground to pin 86.


Fuse F17 (15 Amp) provides 12 Volts to FP Relay pin 30. When the relay is energized, pin 30 connects to pin 87, providing 12 Volts to the Fuel Pump Module, pin 4, which is one side of the pump motor. The other connection for the motor is grounded thru pin 1 of the Fuel Pump Module.

This is all that is required for the pump to run. I never did hear where you were connecting the frame ground to the Fuel Pump. Now, if you ground pin 86 of the Fuel Pump Relay, you will turn the Fuel Pump Motor on if the key is on.

The only connections to the Fuel Pump Module from the PCM should be the 2 wires for the Fuel level Sensor.

 

Friar, The engine and the wiring harness from the hood area and towards the rear of the truck with exception of the cab harness are from the original truck. Does the ASD error shut down the fuel relay. Something has to control the pump as it designed to only run for 2 seconds if engine is not running. I need to find out what has the ASD tripped , the only code displaying other the ASD is P1491 Radiator Fan Ctrl Relay Circ . Thanks for your time and input

 

The PCM has complete control over the Fuel Pump.


I can't see any connection between the ASD Relay output on pin 87 and the Fuel Pump Relay or the Fuel Pump. The circuits for the ASD
relay are the same as my '01.
The output (12 Volts from Fuse 2, 30 amps) from Pin 87 of the ASD Relay powers the Ignition Coil, Fuel Injectors, and O2 Sensor Heaters. It also is fed to PCM Connector 3, Pin 12.


The common thread is the PCM. It controls both relays. However, the controls are from separate wires from the PCM.
The control for the ASD Relay comes from PCM Connector 3, Pin 3.
The control for the Fuel Pump Relay comes from PCM Connector 3, Pin 19.(Unless your engine is Diesel or NGC)


The output (12 Volts from Fuse 17, 15 amp) from Pin 87 of the Fuel Pump Relay powers only the Fuel Pump.


Have you checked for continuity and voltage from end-to-end on these inputs and outputs? Double check these 2 fuses.