02 LW300 V6 Fuel Pump and OBD2 Trouble

[LUXWAG]

Hello, here’s what is going on. 2002 Saturn Luxury Wagon 300 V6 with 113,000 miles has been a very reliable car until now!

What happened?
Turn the key to start, engine turns over and it doesn’t fire up.
I cannot hear the fuel pump prime when turning key to run
Service Engine Soon and Service Wrench light on.

What I did?
I plugged my OBD2 reader into the port and pulled the following codes
-P0201
-P0202
-P0203
-P0204
-P0205
-P0206
(All of those refer to Injector circuit malfunction)
-P0056
(Oxygen sensor heater control circuit, low voltage)

I then cleared all codes and the damn thing fired right up.
I turned off and started the car back up three more times and then went inside thinking it was somehow fixed.

What Happened Next!?

2 hours later i went outside to start the car and the motor turns over and doesn’t start. I turn the key to run and I can’t hear the fuel pump prime. The same service engine soon and service wrench light come on.
And this time the fuel gauge shows empty even though it has a full tank of gas.
So I hooked up my OBD2 reader and now the reader won’t link.

I’ve checked fuses and swapped relays. Charged the battery and I can’t start the car or pull the codes. My code reader works on my other vehicle and every time I hook it up to this car it starts to load but it can’t link up to the vehicle.

I’m guessing it’s a ECM problem.

What do you think?

[fdryer]

Readers do not communicate directly to the engine computer. GMs body control module (BCM) communicates directly to readers/scantools from the OBD II port. The bcm communicates to every module either serially or thru canbus then passes info thru the OBD II port. The gas gauge is driven by the bcm. A blown fuse may be the reason for not connecting to the OBD II port (12v on pin 16). This may be the beginnings of a faulty bcm since it's the gateway for every module thru the OBD II port for determining error codes, programming, diagnostics, etc. Did you check the two inside foot wells for blown fuses too?
The ecm provides the 2-3 second fuel pump signal at ignition on time when the engine isn't started. Depressing the fuel test port for a spray of fuel is one way to check fuel pump operation without a fuel pressure gauge. When the engine's cranking, the ecm turns on the fuel pump from crank sensor timing signals.

How's the main power system - battery, battery cables, their connections? Free of corrosion, snug connections. Battery age? Tested (free) at AutoZone or other stores offering free battery/alternator testing?

[LUXWAG]

Thank you fdryer for the quick response!

I had the battery tested and it was bad. The battery was 5 years old so that was to be expected. I bought a new battery and installed it hoping that was the problem but nothing has changed. No start and the fuel gauge is still on E and the service lights are both on and the OBD2 reader won’t link. I think tomorrow I will check the battery cables and the two interior fuse blocks.

I changed the fuel pump last summer using the “cutting a hole under the backseat” method so I’m fairly confident in the fuel pump working but maybe I’ll try to find that fuel pressure gauge I had laying around and test it out.

[fdryer]

If you have AutoZone nearby, they should have loaner tools like a fuel pressure gauge.

One fuse powers injectors. As a rule, ecm failures are rare but bcm failures do occur according to past history here. If your descriptions are accurate, the bcm may be hinting of impending failure.

The ecm runs the entire EFI system to manage the engine and emissions control. The bcm runs almost everything else except the air bag system and abs/tc. Those have their own independent modules. The bcm drives all interior/exterior lighting, gauges, indicators, manages GMs anti theft system - Passlock, exchanging a password after checking for ignition switch rotation, sending a go or no go signal to the ecm to enable or disable injector operation. In a no go situation, the security indicator flashes quickly - the starter will crank but the engine will never fire up. Normal starting in with the security indicator off. The bcm is the gateway for all error codes from every module.

One way to test for either loss of spark or fuel would be spraying starting fluid into the throttle body. If spark occurs, the engine should fire up and point to possible fuel issues. If the engine doesn't startup oon starting fluid then this tends to point to a spark issue.

[LUXWAG]

So I checked the battery cables and they look ok, no corrosion. I removed the ground to the body and cleaned it up and reinstalled. I checked every single fuse under hood and in the side kick panels. All fuses were good. I had my wife try to start the car as I checked the fuel test port and I had no pressure from the port. We tried several times.

Also after turning ignition to RUN the airbag light comes on and stays on. I don’t know if this is normal.

The OBD 2 still won’t link up.

Also, if the ignition is in RUN I have voltage to the purple wire that goes to the connector on top of the fuel pump. I’m not sure what that goes to, if it’s the pump or the sending unit?

I wonder if I have a bad fuel pump among other problems?

[LUXWAG]

Ok, so I spayed starting fluid into the throttle body and the car started for a couple seconds. Now I’m thinking this is a fuel issue. My first thought is to replace the fuel pump but because the OBD2 reader tool still won’t link up, this may be more of an electrical problem.

[Rj 2000 LS2]

Have you considered the fuel filter is plugged? Disconnecting the fuel filter and testing for fuel pump is working might be good to isolated the a fuel delivery issue.

[fdryer]

Originally Posted by LUXWAG

Ok, so I spayed starting fluid into the throttle body and the car started for a couple seconds. Now I’m thinking this is a fuel issue. My first thought is to replace the fuel pump but because the OBD2 reader tool still won’t link up, this may be more of an electrical problem.

You're describing a possibility of two problems. The suggestion to jumper fuel pump relay socket terminals 30 and 87 to power the fuel pump immediately and try starting accomplishes two things; 1)either the fuel pump runs or not, and 2)if it runs will the engine startup up and stay running? Security must be OFF, not flashing during starting. This assumes the ecm is fine whether or not the bcm is acting up and interfering with the ecm operating the EFI system.

The BCMs role to prevent the ecm from operating as part of Passlock anti theft operation if it sends a fuel password to the ecm to allow injector operation. Operating injectors is an ecm function. Running the fuel pump is also an ecm function. At least once during troubleshooting you were able to get the engine running briefly when spraying starting fluid to verify the ecm is operating. Whether the fuel pump is acting intermittently or failed outright requires testing by jumpering fuel pump relay terminals in the fuse box. The pump must run to supply fuel and pressure to the EFI system. Spraying starting fluid and getting the engine to run briefly seems to point to a fuel pump issue in addition to possible bcm failure. I think you're dealing with multiple issues.

[LUXWAG]

New development…

I tried starting the car again and this time the engine cranks no start (I did not spray starting fluid in throttle body this time) but the fuel gauge now works and the service wrench light does not appear but the reduced power light comes on.

I plugged my obd2 reader into the car and it links up!

Here are the codes…
P0261,P0264,P0267,P0270 (Injector control circuit low voltage)
P0444 (evap emission system purge control valve circuit open)
P0037(oxygen sensor heater control circuit high voltage)
P0057(oxygen sensor heater control circuit low voltage)
P1516(Manufacturer control)
U2105(Manufacturer control) (Transmission code)


What the hell is going on? This has to be an electrical problem coming from the bcm or ecm?