I brought up this problem some time ago but I'm going to try again.

The fuel gage in my '02 will suddenly drop to "E", even after just being filled. Several of you recommended Seafoam and I tried it. It only worked once. I finally bought a code reader from Autozone and tried to find out what code was being thrown. The scanner showed no codes but when I proceeded with the "Clear All Codes, the gage went back to normal and the "Check Gages" light went out. This has happened several times now and is more of a PITA than anything else.

Does anyone have any idea what could be causing this malfunction? I am at my wits end with this. It's obviously not crud on the sensors and even after filling the tank the problem remains until I clear it with the reader.

Any help with this would be greatly appreciated. Thanks in advance.

Jim

 

I know many on here suggest Seafoam, and I don't understand why. There is NOTHING in Seamfoam's documentation that suggests it cleans sulfur from fuel sending units. While techron specifically states it does.

 

I've tried both Seafoam and Chevron with Techron and neither helped the situation. There is something somewhere that is causeing the computer to "see" that the tank is empty and to cause the guage to drop. It is really weird. The last time it happened, last Sunday, there had been no problem for weeks. While on the way to Inglewood for a pistol match it suddenly happened. This occurrance coincided with my turning the cruise control off then on but I can't be sure that it is connected. I'll try that again when I get the chance and see if the problem rears its ugly head again. I'm tempted to just keep the reader connected so I can clear it on the move. Very frustrating.

 

To be clear...not chevron gas w/techron....rather... a bottle of concentrated Techron fuel additive.

 

I understood what you meant but the Seafoam crap was bad enough at $11+ per bottle. I simply don't think that that is the problem.

 

If that's what you believe, I suggest you do a forum search.

 

You can clear it using the DIC ... and can even clear it while the car is running if you want your gauge to come back.

Try some Redline SI-1 Fuel System Cleaner ... seems to help also.

 

I'm sure you are aware there was a TSB for this issue, which involved reprogramming the PCM.

By the way, a code reader is not necessary on a C5:

http://www.c5forum.com/ayc/dtcdic.php



good luck

 

No, I wasn't aware of the TSB. I'll have to check into that. I bought the code reader for all my vehicles and it, at least, gave me an idea what the problem was (not crud on the sensors). It DOES allow me to remove any codes that pop up. Thanks.

 

What code showed up when the gauge went to "E"?

 

Strangely enough, there were no codes shown, even on the external code reader. The fuel gage just suddenly dropped to Empty, the "Check Gages" light came on and the DIC said "Low Fuel". I have not been able to ascertain any specific time or fuel quantity associated with this. When I plugged in the external code reader it said "No codes available" or something like that. The first time I used it I just said "What the heck" and went through the code erase procedure and, lo and behold, the gage popped back up to where it was supposed to be, the light went out and the DIC went back to normal. It's really weird. I sent an email to Chevrolet some time ago but it was, of course, never answered. I guess Obama side tracked it. http://images.ibsrv.net/ibsrv/res/sr...lies/wink5.gif

 

Spooky, if you want some help, go back and read post #8. Then post the codes, ok?

 

Exactly. Many code readers will not read ALL the codes. That's why it's best to check through the DIC

 

Thanks, Byronhunter, I missed the link the first time through. In a hurry I guess. I printed out the instructions and will give it a try and see what happens. Maybe that will also allow me to turn off that damned "Service Tire Monitor System" display I get every time I start the thing. I don't know yet whether the previous owner removed the sensors or it's just that the batteries are dead (I'm hoping for the latter, it's cheaper to fix). I just haven't had the time or money together to investigate it.

 

I went back and ran the DIC code search and the question, instead of what code showed up, should be what code DIDN'T show up. There were 17 codes in the thing. I don't know if the one for the fuel gage is in there somewhere but here's the list:

80 Radio
U1000H (X2)

A0 LDCM
B2282H
B2284H
U1064H

A1 RDCM
B2283H
B2285H
U1064H

AC SCM
B0851H
B0856H
B2605HC
B2607HC
B2606HC

B0 RFA
C2100HC
C2105HC
C2110HC
C2115HC

Now all I have to do is look all those up somewhere. Either that or say to heck with it and clear everything and start over. :-)

I can understand the AC SDM codes since the original owners brother ripped the motors and stuff out of the drivers seat and made a freaking bar stool out of the seat when the owner put the racing seat in but the others are going to take some research.

Thanks for the help, guys. I'm fairly new to all this computer stuff because I'm used to working on cars that you could actually work on.
I have GOT to order the shop manual for this beast, that's all there is to it.

Jim

 

The link I provided you has links for various year at the bottom of the page....so you can find out what the codes mean.

 

That looks to me like the sensors were removed. Do you have after market wheels? If so, it could be the PO didn't fit sensors.

The way the system works is that the sensors send a signal to the receiver (shared with the door lock system) once the car is moving. The computer interprets the voltage and sends a pressure value to the DIC. To have all four sensors failing to communicate would be unusual. If batteries fail you get a XXX reading for that sensor on the DIC.

Edit: I see you have Z06 alloy wheels.

 

Coming back to your original problem Jim. Trust the advice you've been given. It is without doubt a common problem and can normally be easily fixed.

Here's a copy of a post I made in another thread with the same issue

The dead gas gauge is a common problem here. Normally the symptom is that it will fall to zero. In my case, the first time it happened I filled to full but the gauge showed 3/4 and slowly rose to full. I treated it quickly and it cleared. I've since had a "drop to empty" when I ran the tank low on one occasion.

You can see from this picture how the sender works. The floating arm runs over pick offs and depending on the amount of fuel sends a different resistance to the computer to gauge the gas. The right tank pumps fuel to the left from where it feeds the engine. The computer averages the contents of both tanks. The problem is that sulfur in the gas fouls the pick offs causing a bad reading.



In your case it's working initially with a full load.

The easy solution is to treat it with Techron (or some prefer Seafoam). If it's only slightly fouled Techron will clear it quickly. If it's been a while with those symptoms and it's badly clogged it may take a number of treatments to clean it. If it's really badly fouled you may have to replace the senders. Theres one in each tank.

Try Techron first. The other thing to do is to check the codes and clear down any fuel related problems.

Report back but give the Techron time to work

 

Jim,

The relevant codes are the ones with C posted behind the numbers. The H codes mean "history". In other words, the fault was present but has run enough start up cycles where it's not present that the PCM closes down the code.

Turning to the ones that you still have active:

AC SCM
B2605HC
B2607HC
B2606HC

B0 RFA
C2100HC
C2105HC
C2110HC
C2115HC

• B2605 Seat Front Vertical Position Sensor Failure
• B2606 Seat Rear Vertical Position Sensor Failure
• B2607 Seat Horizontal Position Sensor Failure

As you rightly say, if the PO removed the seat motors these codes will flag up.

The other currect codes are related to the tire pressure system and again, if they've been removed you'd expect this:
• C2100 Left Front TPM Sensor Malfunction
• C2105 Right Front TPM Sensor Malfunction
• C2110 Right Rear TPM Sensor Malfunction
• C2115 Left Rear TPM Sensor Malfunction

This makes me think that my previous diagnosis may be correct.
C2120 TPM System Malfunction (No Sensors Received) and/or C2121 TPM System Programming Malfunction (No Sensors Programmed) would probably be flagged if there was a problem with the RFA (RF receiver). Looks to me like it's working OK but there are no sensors to give a reading. The way to check is if the door lock system is working normally, the RFA is working. As I said, it's a shared function.

Just out of interest the door lock module codes are unusual and only flag up as history codes. They cant set as current(C).
There are a couple of things in the manual that you might want to check out.

DTC B2282-B2285
Circuit Description

The driver door module (DDM) and passenger door module (PDM) each have a high and low power feed . The low power feed, battery 1, is used to provide power for the door module logic and internal driver operation. The high power feed, battery 2, is used to provide power for systems that draw higher amounts of current. The door modules monitor the voltage level at battery 1 and battery 2 to determine if the voltage level is out of range. If the voltage level is out of range, a DTC is set.
Conditions for Setting the DTC

* The door module detects battery 1 or battery 2 voltage range under 8.5 volts or over 16.3 volts.
* Condition must be present for greater than 2 seconds.

Action Taken When the DTC Sets

* Stores a history DTC B2282, B2283, B2284 or B2285 in the door module memory.
* These DTCs can only be set as a history code even if the malfunction is current.
* No driver warning message will be displayed for this DTC.

Conditions for Clearing the DTC

* The door module no longer detects battery 1 or battery 2 voltage below 8.5 volts or higher than 16.3 volts for greater than 2 seconds.
* The DTC is cleared using the IPC clearing feature, or
* The DTC is cleared using a scan tool.

Diagnostic Aids

* The following conditions may cause an intermittent malfunction:
o There is an intermittent open or short to ground in a battery 1 or battery 2 circuit.
o The battery voltage is out of range.
o A charging system malfunction.
* Using a scan tool, select DCM Data display and monitor battery 1 and battery 2 voltage while operating the door locks and heated mirrors. This can determine if battery 1 or battery 2 voltage is affected by these devises and can help duplicate the malfunction.
* If the DTC does not reset after the code is cleared, then the problem may be intermittent

U1064 often sets if you have any type of power glitch. Another common problem with this car is that the wires in the door hinge area can chafe and cause electrical issues. Pull back the rubber gaiter and make sure that you don't have any damaged wires. Clean and reseat the electrical connectors.

Once you've done that, clear the codes and see if the H codes come back. Obviously the ones where the components have been removed will reappear.

Hope that helps.

 

Since the Seafoam worked once( we have used it in the shop for years for just this problem) it does indeed seem like sulfer build up is the problem.Sometimes it takes more than one dose to cure it.