jodybare

Sorry for the delay. I finally had time to check the suggestions above.

1) Replaced Relay (note I could hear it clicking with the key turned) - with relay removed, am getting 12.3 V on pin 30.
2) Jump pin 30 to 87 with key in run- DVOM on the power and ground pins of the fuel pump wiring harness gets 12.3 V constant.
3) LED tester on pins 86 and 85 does light up when key is in 2 position for about 2 seconds. On continuously when starting the engine.
4) with Fuel pump harness hooked up to the sending unit - with key on, still no pump start - nothing.

Is this some kind of wiring harness issue? I wonder if replacing the wiring harness on the sending unit might get this fixed? Is it possible to even buy one?

bbirdwell

If I read the above correctly, you are getting the proper voltages.
Line 1) good.
Line 2) good. Tells you that you have connectivity between the relay socket and the fuel pump; you're getting good voltage at the fuel pump connector.
Line 3) good.
Line 4) not good. Indicates that even with good voltage at the connector, when the connector is attached to the fuel pump, the fuel pump does not run; indicative of a bad or burned out fuel pump or the internal plug in the tank is disconnected. All connections, power, and ground appear to be good. That points to the pump inside the tank. Stupid question here but it has happened in the past...are you sure the fuel line in the tank is still attached to the fuel pump? This is the line with which the fuel pump feeds the fuel filter/regulator on the driver's side. There has been at least one instance where the individual changed the fuel pump, the fuel line connector was not snapped into place and, when he keyed on, the fuel line connector popped off of the fuel pump. So...open the tank on the passenger side, verify the internal electrical plug is connected, and verify the fuel line is attached to the fuel pump.
-You should pull the driver's side sending unit and check the electrical connector on the side of it (the connector located inside the fuel tank, not the external connector). If that is loose, then it would make sense that both floats are giving erroneous readings (if any) *and* the fuel pump would not run. I'm beginning to think this is the common failure point. In fact, this would be the first place I would check.

On the fuel pump connector (should be pin 5), the 2.5mm Brown wire is grounded in the left rear wheel well. Ensure you can place the DVOM lead on that pin and you have continuity to chassis.
On the fuel pump connector (should be pin 2), the 2.5mm Red/Green wire should be your power lead. That should be connected to the fuel pump relay connection in the rear SAM (connector 1, pin 3). Key on, it goes positive for 1-2 seconds; key start position, it goes positive so long as the motor is turning over.
On the rear SAM, connector 1, pin 7 is the lead (Brown/Green) from the Motor Electronics that activates the relay.

Pin 1 of the fuel pump connector is common for the two floats. Pin 3 is the readout for one float and pin 4 is the readout for the other float.

Poor shot but my diagnostic computer never touches a network. M3 is fuel pump, B4/1 and B4/2 are the float sensors, N10/2 is the rear SAM, the motor electronics black box is at the top of the picture. W6 ground point in is the left rear wheel well somewhere.

jodybare

Thanks this is very helpful.

I will pull the sending unit tonight and check.

However, I am not sure that is the issue here. I can hook up the #2 pin (red/green -power) and #5 (brown - ground) with alligator clips from the harness directly to the #2 n #5 pin on the sending unit and the pump works and the car starts. the pump spins up for 2 seconds with the key in on position. Car starts and pump runs with the key turned on.

Also, when I plug in the harness, I can see the fuel level gauge (instrument panel) go the half full (which is approximately what it actually is). However, the low fuel light still stays on.

I am wondering if the problem is pin #1? It does seem like it is something with one or more of the 3 sensor wires (1 , 3 or 4).

Also, as soon as I clear the error codes on the ME (P2003A-008 - fuel tank level : See tank level sensor (P1999) and the 9085 and 9086 on the Rear SAM (fuel gauge sensor) they come back immediately.

I will report back as soon as I pull the sending unit and confirm that the internal plug and wiring are secure.

At that point, we should be able to isolate it

jodybare

I was able to pull the sending unit and went ahead and pulled the pump as well. I checked all wires and harnesses internal (sending unit and pump). Unfortunately they were all connected well and I didnt see anything that looked like it could be an issue.

Again since I can get the pump to run from the harness by using a wire and alligator clips to pins 2 and 5 (bypassing 1,3 & 4 on the harness) I suspect this is a wiring issue in either 1,3 or 4? I am going to start trying to trace the wires back to their respective connection points? I am not sure how I will measure continuity given the distance from the harness to the trunk, etc...

Any thoughts?

jodybare

After spending a good bit of time, I was able to trace each wire through the bundle back to the SAM and could not find obvious issues with the wires.

I am not sure how to check continuity for the each wire because of the distance and how I would probe the wires.? Any suggestions?

I am again wondering if somehow the contacts inside the harness might be bad and not making proper contact? I have probed them alot of the last few weeks?

So once again, I am seem to be at a dead end. This is so frustrating. I guess the good news is we have probably isolated it to the wiring.

Any advice on where I go from here?

sarcophagus

did you get your problem resolved? i am asking because i got exactly the same codes and you're the only one who came up when i searched for the codes re P203A-008 P1999.