Engine/Transmission (1998.5 - 2002) Erratic Fuel Pressure and P0230

[turbo torque]

I receintly moved lift pump to the rail. I used 16 gauge wire to lengthen the harness. Put 500 mi. with no issue. Now, pressure is all over the board, even down to ZERO. Pump and filter is new, even changed back to old pump.



Throwing a P0230 Lift Pump Voltage Any Ideas? Thanks, Bill.

 

[JLandry]

Bill,



Likely something is wrong with the lift pump wiring harness.



Check the harness for shorts, grounds, or an open circuit.



From the Dodge Diagnostic Manual:



P-0230 TRANSFER PUMP CIRCUIT OUT OF RANGE



POSSIBLE CAUSES

• FUEL TRANSFER PUMP GROUND CIRCUIT OPEN
  
• TRANSFER PUMP POWER FEED CIRCUIT OPEN
  
• TRANSFER PUMP POWER FEED CIRCUIT SHORTED TO GROUND
  
• ENGINE CONTROL MODULE
  
• FUEL TRANSFER PUMP (GROUND CIRCUIT)
  
• FUEL TRANSFER PUMP (POWER FEED RESISTANCE)
  
• FUEL TRANSFER PUMP (POWER FEED VOLTAGE)
  
• FUEL TRANSFER PUMP RESISTANCE OUT OF RANGE)
  

 

[turbo torque]

All I did to the harness was splice a new 6 ft. 16 ga. extention cord, soldered and heat shrink. Put dielectric grease on the plug in ends. I think voltage is erratic, the pump sounds terrible when pressure is down to 2 or 3 lbs. when pressure comes up to 12, the pump sounds good. Could the heaver ga. wire cause this? Can I run 12 v from the battery to pump? I'm out of town and need to get down the road

 

[JLandry]

All I did to the harness was splice a new 6 ft. 16 ga. extention cord, soldered and heat shrink. Put dielectric grease on the plug in ends. I think voltage is erratic, the pump sounds terrible when pressure is down to 2 or 3 lbs. when pressure comes up to 12, the pump sounds good. Could the heaver ga. wire cause this? Can I run 12 v from the battery to pump? I'm out of town and need to get down the road

Chances are there's something wrong with the new extension you made.



The proper thing to do would be to disconnect the harness at the pump and actually measure the voltage at the connector. If it's not 12+ volts, you would then want to continue trouble shooting the wiring harness until you figure out what's wrong. You could do a voltage drop test at various points along the harness. This would be done with the harness connected and the pump running. You would put one voltmeter probe on the wire harness close to the ECM and the other near (or at) the pump, or as far as the probes will reach apart. This should be done on both the positive and negative leads of the harness. If the wire being checked is good, the voltmeter will show little or no voltage. If the wire has a break or any significant resistance in it (a problem), the voltmeter will show up to 12+ volts.



Another test is to measure the resistance between the negative lead of the connector at the pump and the frame of the truck to verify this lead is properly grounded.



If you don't already know, the fuel pump can be turned on for 25 seconds by bumping the starter, but not starting the engine.



You can run an emergency power lead to the lift pump from the battery, but you really need to use a relay to control this new circuit because the lift pump can pull some amps (I forget how much at the moment). You'd want to control the relay from a circuit switched by the ignition key when placed in the run position.



Good luck,



John L.

 

[jhoughton]

With my FASS system it uses a relay that is wired to the original lift pump wire that triggers a relay. The power to the pump is hooked directly to the battery. With this the ecm still controls the 3 second and 30 second timer during start or bump cycle.

 

[turbo torque]

I borrowed a brand new harness from a buddy that bought the relocation kit from genos. It does the same thing, anyware from 0 to 13 psi. It can go 100 mi. at 13 then to 2 or 0 psi. Pressure is verified w/snap-on mechanical gauge, pre-filter. I'm at my witts end. Could it be the ecm? How do I test ecm? Thanks in advance, Bill

 

[JLandry]

Could it be the ecm? How do I test ecm? Thanks in advance, Bill

Bill,



If I understand you correctly, this problem is very random and the condition isn't necessarily occurring with the truck parked in your driveway? That sure makes it tough to diagnose.



Also, while you've verified the fuel pressure is indeed dropping out, you still didn't mention if you've verified the lift pump is actually getting 12+ volts or not when this problem occurs.



Assuming the lift pump *is* NOT getting 12+ volts when the problem occurs... then you've eliminated the wiring harness extension as the culprit by replacing it. But unless I missed something, you still haven't eliminated the stock section of the wiring harness (from the ECM to the original lift pump connector)... right?



It could very well be the ECM that's at fault. I believe it uses 2 separate transistors to switch power on and off to the lift pump. I'm sure these can go bad. But before you assume that's the case, due to the replacement cost of an ECM, you really need to positively eliminate the stock wiring harness as the cause.



Here's what I'd do next:



Disconnect the wiring harness at the lift pump's original connector. Insert (or clip) the leads of a voltmeter on the two pins of this connector. The yellow/white wire is positive (+) and the black/white wire is negative (-). Activate the lift pump for 25 seconds (bump the starter) and check for 12+ volts at the connector while you wiggle and twist the wiring harness (from the ECM to the connector). You're trying to find out if there's an intermittent break somewhere in the wiring harness.



If that doesn't reveal anything, remove the 50 pin connector from the ECM. You'll need an Allen wrench to turn the hex head cap screw embedded in the center of the connector. Turning this screw slowly backs the connector out from the ECM socket. Once you have the connector out, check for continuity (a good connection) between pins 15 and 35 of the wiring harness. These two pins together supply 12 volts to the lift pump and are connected together somewhere inside the wiring harness before the lift pump connector. Also check for continuity between each of these pins individually and the pin for the yellow/white wire at lift pump connector. Also check for continuity between the ground pin (black/white wire) of the lift pump connector and the negative terminal of the battery. While making these checks, twist and wiggle the wiring harness if you can.



#ad




If all of these tests turns up nothing abnormal, then you have to assume the ECM is going bad. You have your choice of replacing it or just wiring in a new circuit for the lift pump with a relay switched by the ignition key. If you decide to resort to that, let me know and I can give some suggested places to connect the wires.



The downside to creating a new circuit is the lift pump would continue to run even if the engine stalled and stopped running for some reason... like in an accident, etc. The ECM will turn off the lift pump if the engine dies and the ignition key is in the run position.



A refurbished ECM can be purchased programmed for your truck and reaqdy to install from "Auto Computer Exchange" on eBay for only $495 delivered. I've dealt with them personally and they were a good company to work with.



I hope that helps.



Good luck,



John L.

 

[turbo torque]

Thanks much John, I will try this procedure, next time it happens. Today, it happened right at home. I'm not against creating a new circuit w/relay and sure could use some tips in doing so. The electric end is my weaker side

Thanks, Bill

 

[JLandry]

I will try this procedure, next time it happens.

Maybe the attached wiring diagram of the lift pump circuit will help during your testing.

I'm not against creating a new circuit w/relay and sure could use some tips in doing so.

If you have to resort to that, all you need to do is find any wire in engine compartment on the driver's side which has 12+ volts of power when the ignition switch is in the RUN-START position. There will be many such suitable wires in the wiring harness coming out of the PDC (Power Distribution Center). I've created a wiring diagram showing how you would add a relay and new wiring circuit for the lift pump.



Regards,



John L.