P1626 Theft Deterrent Code question?

[97LT4SS]

Attempted to take the Camaro out for it's first ride since last summer, but battery was dead. I jumped it while in my garage and it fired right up. Battery was very weak during winter start-ups but figured all it needed was a long drive to recharge.

Arrived at work with no problems during the drive. End of the day, the engine would crank but not fire...battery eventually died. Luckily I'm fairly close to an Auto parts store so I buy a new battery and install. Car would still not fire up, cranks fine but cannot hear the fuel pump. Return battery and have the car towed home. Recharged the old battery and still no luck. Neighbor has a GM Tech and P1626 was present so he cleared and motor fired right up only to die shortly thereafter.

Broke open the owner's manual and took out the spare key and again erased P1626. Motor started right up and ran for at least ten minutes. As before it eventually stalled and will now only crank.

SES is not on and the Security light goes off 5 seconds after the ignition is turned on. I can start the car by disconnecting the battery but it dies after 2 or 3 start-ups. I'm stumped at this point.

Should I purchase a new battery and have the P1626 cleared again?
I have also been experiencing an intermitten P100 MAF code which I'm not sure is related to the P1626. SES is currently not on.

Car is a 1997 Camaro LT4 SS with 20k miles.

Thanks in advance for any ideas or input.

[Joe 1320]

Have you checked the fuel pressure and volume? correct pressure should be 44 psi +/- a couple psi at idle and should not drop as rpms and load increases.

[97LT4SS]

No, I haven't checked the fuel pressure...honestly not sure how too. Why would fuel pressure fluctuations, if that's the problem, trigger P1626?

I'm glad you mentioned fuel pressure, because the shop which performed my mods a few years back told me the fuel pump was at it's limits and needed to be upgraded soon. This was Dec 2006, maybe I've put 500 miles in the car since they installed SVO #30 injectors at that time. The shop said fuel was being cut-off above 6k while on the dyno, which is why they suggested replacing the fuel pump. Like I said this was 1 1/2 years ago.

Not sure if P1626 is related or not. I would have replaced the pump myself but I do not have access to a lift.

Thanks,
Eric

[Joe 1320]

No, I haven't checked the fuel pressure...honestly not sure how too. Why would fuel pressure fluctuations, if that's the problem, trigger P1626?

I'm glad you mentioned fuel pressure, because the shop which performed my mods a few years back told me the fuel pump was at it's limits and needed to be upgraded soon. This was Dec 2006, maybe I've put 500 miles in the car since they installed SVO #30 injectors at that time. The shop said fuel was being cut-off above 6k while on the dyno, which is why they suggested replacing the fuel pump. Like I said this was 1 1/2 years ago.

Not sure if P1626 is related or not. I would have replaced the pump myself but I do not have access to a lift.

Thanks,
Eric

I don't know if the code is related or not.

The reason I mentioned the fuel pump was that the symptoms sounded much like what a very tired fuel pump might produce. Since you hadn't mentioned anything about fuel modifications, I put 2+2 together.

the fuel pressure access port is located on top of the intake manifold, just behind/under the cowl. You can probably get a free loaner of a fuel pressure tester kit at Autozone.

[97LT4SS]

Good point...maybe a tired fuel pump could trigger P1626...not sure?

[Injuneer]

From Shoebox's code list:

P1626 = Theft deterrent system fuel enable circuit

The fuel pump isn't working because the circuit that enables the fuel pump to start is not being completed. Not the other way around.

Check the fuse for the fuel pump since that also supplies the PCM and in some years the theft deterrant system and the MAF sensor. The 97's seem to have a problem with the pink wire that supplies 12V to the MAF harness connector. The wire breaks somewhere in the harness, and you don't get any voltage at the harness connector for the MAF. Key on, check for 12V between the pink wire in the MAF sensor connector and the black/white ground wire.

You can bypass the theft deterrant system fuel pump permit by running the pump using the gray fuel pump prime connector near the PCM. Just supply 12V directly from the battery to the gray connector. If you can put a 20A fuse in the wire from the battery, it will be safer.

[97LT4SS]

Thank you for the reply Fred. If the fuel pump fuse failed then how could the car start after the battery is reconnected? Reason I ask is because when the battery is reconnected the motor starts.

Would I have to splice into the gray fuel pump primer connector in order to run 12V from the battery?

Eric

[97LT4SS]

Fred, where is the gray fuel pump primer connector and the fuel pump fuse located? I only have Service Manual 2 of 2 so I need some direction please.

Thanks again

[97LT4SS]

I think the fuel pump can now be ruled out, because after disconnecting the MAF and re-connecting the battery the motor ran perfect (other than the P100 code) for at least an hour.

How do I go about repairing the Pink wire to the MAF...that has be the problem? Could P1626 be related to the initial P100 code?

Thanks

[Injuneer]

Fuel pump prime connector - should be in the same place on your 97:

http://shbox.com/1/fuel_pump_prime.jpg

I don't have the detailed breakdown on P1626, just what I posted above. But the fuel pump relay gets a signal from the PCM in order to start the pump. The PCM is telling you its either not sending that signal, or the circuit (wire from the PCM to the relay or the signal side of the relay) is not good. It may be an intermittent problem. I don't see the PCM setting that code if there is no MAF signal. I've seen a lot of scans that show the P0100 code, but never with the P1626. In fact, I don't think I ever saw P1626. I have a diagnostic list right off the GM tech website, and they don't even list it for the 97. But Shoebox has it listed, as does Chiltons, so its a valid code.

Have you checked the connector for the fuel pump relay? Or checked the relay?
Again, from Shoebox:

http://shbox.com/1/fuel_pump_relay.jpg

Most people fix the pink wire problem by running an additional wire directly from the correct fuse to the MAF harness connector. The same circuit provides power to multiple loads, so the break has to be somewhere in the harness after all those other loads split off. I can't remember anyone tracing it down to an actual location. And its really odd that is only the 97's that seem to have that problem.

[97LT4SS]

Fred, again thank you.

The Pink wire going to the MAF is reading 10.98V, does it have to be exactly 12V? The Yellow wire is reading 5.04V.

Motor currently has a cleaned 5 year old Granatelli MAF, but it runs the same with the original MAF.

If I need exactly 12V should I run a wire from the "ENG SEN" fuse under the hood directly to where the Pink wire connects to the MAF sensor?

I have NOT checked the connector for the fuel pump relay or the relay itself. Is the fuel pump even a concern at this point since the motor ran for an hour last night while the MAF was disconnected?

Thanks,
Eric

[97LT4SS]

Fred,

The Pink wire coming out of the "ENG SEN" fuse is only reading 11.54V not 12V, is this a problem?

Thanks,
Eric

[Joe 1320]

11.54 is close enough to be considered a valid 12V.

One thing to keep in mind..... if everything else checks out, it might be the PCM. Any chance you have a spare?

[97LT4SS]

Joe,

No spare and the original PCM (which is still in the car) has a custom Superchips tune so I don't think the motor will run with a stock PCM?

Do OBD II motors have MAF relays like the TPI engines?

Thanks,
Eric

[Injuneer]

The 4th Gen MAF's do not have the relay. That was required for the Bosch MAF sensors used in the 3rd Gens, for the "burn off" system. There is no burn off system on the GM MAF sensor used in the 4th Gens.