TheProsecutor

Installed the ACDelco MU1216 GM Original Equipment Fuel Pump and Level Sensor Module and the ACDelco SK1318 GM Original Equipment Fuel Level Sensor Kit with Sensor, Float, Filter, Clip, and Seal.
I still have no fuel gauge
I get the two normal codes.
Fuel filter is new also.

This was fixed by replacing the wire at the PCM.

Pounder

not sure it would show with codes but I would check ??

Pounder

missed the codes, sorry, does the gauge sweep to full when the key is turned to on ??? I'm not sure on our cars but the old days you grounded the sender wire to see if gauge worked (would go to full or beyond)

oelarse

Here is the fuelsensor wirings for 99

69

May want to check each level sensor to see if it is actually reporting fuel levels to the PCM using a Ohm meter.
Check out my fuel table post in this thread for troubleshooting a "99 Vette
https://www.corvetteforum.com/forums...nder-says.html
Post up what you find and/or readings for further troubleshooting.
Goose

Bill Curlee

There is an entire chapter in the OEM Service manual on fuel gage troubleshooting. Until you get a meter on the circuit, you wont know much more than you do now!

Start by reading the resistance and voltage on each sensor.

BC

TheProsecutor

Thanks for the information. I had two years of electrical engineering before switching majors. I will troubleshoot it this weekend, before the Superbowl.

midnight01

Did you replace the right hand side pump or the main driver side? those look like symptoms of the passenger fuel level sensor is bad. My 01 had the same type of problem as yours. I replaced the passenger assembly and the problem cleared right up. In our cars gas goes to the right tank 1st then as fuel runs out of the driver side the right side pumps it over to keep them both level. When your gauge says half a tank, the right tank is empty. So it sounds like the right hand level sensor is the problem.

TheProsecutor

I replaced the passenger side pump this week. I replaced the driver's side sensor last year. I didn't have enough money last year to replace them both. Both are replaced.

69

After further review of this thread there some points that need clarification so that we can help you with a good fix and restore you fuel gauge operation.
Question> Before you replaced the left/right fuel tank sensors, please describe the fuel gauge behavior.
The left full level sensor was replaced last year>
Question> was the left full level sensor replaced because the fuel gauge reading empty with fuel in the tank?
Question> after replacing the left full level sensor, did the fuel gauge reading or behavior change?
I suspect that the fuel gauge reading or behavior did not change, therefore you replaced the right fuel pump/sensor to regain fuel gauge readings, is this correct?
Way forward>
With fuel in the tanks, perform continuity checks of both left and right fuel level sensors, pay specific attention to the left sensor, , (perform readings at the yellow plugs on the sensors)record the readings from the Ohm meter, post up your reading results.
Drain as much fuel from the tanks as you can, perform continuity checks of both left and right fuel level sensors, pay specific attention to the left sensor, , (perform readings at the yellow plugs on the sensors) record the readings from the Ohm meter, post up your reading results.
What we are looking for here is to see if the left and right sensor signal values are changing and if the values are going in the correct direction when compared to the fuel table in my previous post.
Left sensor alligator!
I have sorted out a few C5 fuel gauge issues and in one case, the fuel level sensor BLUE pin wire was not locked in the plug resulting in an “open”, discovered upon assembly removal from the fuel tank and in another case, the BLUE and GREY wire pins were locked in the plug BUT the BLUE and GREY wire pins were crossed (wrong positions in the plug).
I don’t want to assume you may have a crossed or disconnected wire issue here, but please be prepared to go into the tanks to sort this issue out.
Post up your findings, there is a lot of talent on this board, we will get you to a solution.
Pics of a left sensor swap for those following this thread.
Cheers,
Goose

TheProsecutor

Ok, I will take measurements and pictures of the wiring. It might take several weeks, as I drive it only 13-26 mile per day and I just filled up the tank.

TheProsecutor

Question> Before you replaced the left/right fuel tank sensors, please describe the fuel gauge behavior.
ANSWER> Always on E. Resetting the code did not cause the gauge to even move.

Question> was the left full level sensor replaced because the fuel gauge reading empty with fuel in the tank?
ANSWER> YES.

Question> after replacing the left full level sensor, did the fuel gauge reading or behavior change?
ANSWER> CORRECT, behavior did not change. So I replaced the right fuel pump/sensor to regain fuel gauge readings, correct.

I will check the continuity on the left and right fuel level sensors.
QUESTION> Am I measuring the resistance between ground and the yellow plug?
I will post up my results.

I will check the fuel level sensor BLUE pin wire to see if it is locked in the plug resulting in an “open”

I will check for BLUE and GREY wire pins crossed.

I don’t want to assume you may have a crossed or disconnected wire issue here, but please be prepared to go into the tanks to sort this issue out.

69

Hello, to follow up on your questions;

QUESTION> Am I measuring the resistance between ground and the yellow plug?
I will post up my results.
Answer> to properly measure the resistance of the left/right senders, the systems electrical wires need to be configured for voltage/resistance checks, proceed as follows;
Make sure the car’s key is in the “off” position as we do not want any voltage on the system at this point.
Disconnect the chassis wire harness plugs from the left and right fuel senders.
Referencing the below schematic, (red box area at the sensors) the following applies;
PIN “B” is the left and right sensor ground signals.
PIN “C” is the left and right sensor power signals.
Staring with the left (drivers side) sensor, measure resistance on the sensor yellow plug between PINS “B” and “C” and post up your values.
Measure resistance on the sensor yellow plug between PIN “B” and chassis ground, (expectation here is to have an “open” or NOT shorted to ground). post up your result.
Measure resistance on the sensor yellow plug between PIN “C” and chassis ground, (expectation here is to have an “open” or NOT shorted to ground). post up your result.
Next>
Staring with the right (pax side) sensor, measure resistance on the sensor yellow plug between PINS “B” and “C” and post up your values.
Measure resistance on the sensor yellow plug between PIN “B” and chassis ground, (expectation here is to have an “open” or NOT shorted to ground). post up your result.
Measure resistance on the sensor yellow plug between PIN “C” and chassis ground, (expectation here is to have an “open” or NOT shorted to ground). post up your result

Now we will need to check the left and right sensor’s ground signals/chassis wiring run to the PCM to ensure that is serviceable, proceed as follows;

Staring with the left (drivers side) sensor chassis harness plug , (the plug that you attached to the sensor) measure for continuity to ground on PIN “B” (Ohm meter probe on chassis other probe on PIN “B”) post up result, expectation here is that you should have continuity.
NEXT>
Staring with the right (pax side) sensor chassis harness plug , (the plug that you attached to the sensor) measure for continuity to ground on PIN “B” (Ohm meter probe on chassis other probe on PIN “B”) post up result, expectation here is that you should have continuity.

Now we will need to check the left and right sensor’s power signals/chassis wiring run to the PCM to ensure that is serviceable, proceed as follows;
Place key in RUN position to send power down the lines to the sensor plugs.

Staring with the left (drivers side) sensor chassis harness plug , (the plug that you attached to the sensor) measure for power to ground on PIN “C” (volt meter probe on chassis ground other probe on PIN “C”) post up result, expectation here is that you should have voltage.
NEXT>
Staring with the right (pax side) sensor chassis harness plug , (the plug that you attached to the sensor) measure for continuity to ground on PIN “C” (volt meter probe on chassis ground other probe on PIN “C”) post up result, expectation here is that you should have voltage.

Tips> May want to perform the above test 3 times to ensure accuracy of the testing results and values. Additionally it is very important to understand the proper Ohm/Volt meter operations with respect to “power and ground” and the red/black probes of the Ohm/Volt meter to avoid negative readings and negative values.

Before you dive into or open up the fuel tanks, perform these tests and post up your results and values, we want to make sure nothing silly is going on with the circuit such as a broken ground point at splice group S410 which is preventing the ground signals from reaching the left/right sensors.

Cheers,
Goose

TheProsecutor

I removed the driver side fuel pump.
I noticed that I had the grey and the blue wires reverse to what is shown in the above picture.
I removed and installed the wires correctly.

With the pump outside the tank, I bench tested it.
With a DMM, I measured the resistance of the left sensor, across the board and across B and C.
PIN “B” is the left ground, the grey wire.
PIN “C” is the left power signal, the blue wire.
The resistance in a full sweep was 42 ohms at empty and 250 ohms at full. The resistance varied with greater change as it approached empty.

I was hoping that reversing the blue and gray wire would solve the problem it did not.

The gauge sweeps full when turning the car on.
The fuel pump/s work.
I can drive until 17+ gallons are used.
After reset of the codes, without starting up, I get 1/2 tank of gas reading.
However, once the car is started, it drops to empty.
These readings are identical to the behavior before reversing the blue and gray wires.

Next time, I will post up more readings from the pax side.

LoneStarFRC

In addition to the very good advice being given and your steps taken, I would also recommend locating Splice pack S410 and verifying it being corrosion/oxidation free. If necessary, I would even open it up or disassemble it to check. Like others have mentioned, I'm thinking "commonality" since you have problems associated with both sides (driver/passenger) of the system. Corrosion/oxidation issues or intermittent opens, as we all know, can have the electrical "effect" of becoming a variable resistor.
In my working on and around my fuel system myself, I don't recall the exact location of S410, mainly because I didn't have to deal with it specifically, but I suspect it is one of the common black/gray splice packs typical of those used elsewhere all over the C5. According to the schematic, it will have four gray wires going into it.

Next would be continuity checks between/to connectors C402 pin C and connector C142 pin S and of course lastly PCM (blue connector) pin 23.

HTH

TheProsecutor

I finally got around to do this finally.
1. Drivers side sensor, measure resistance on the sensor yellow plug between PINS “B” and “C”.
a. 40.7 ohms – empty tank, this seems right
2. Measure resistance on the sensor yellow plug between PIN “B” and chassis ground
a. open
3. Measure resistance on the sensor yellow plug between PIN “C” and chassis ground
a. open.
4. Pax side sensor, measure resistance on the sensor yellow plug between PINS “B” and “C”
a. 40.7 ohms – empty tank, this seems right
5. Measure resistance on the sensor yellow plug between PIN “B” and chassis ground
a. open
6. Measure resistance on the sensor yellow plug between PIN “C” and chassis ground
a. open
7. Drivers side sensor chassis harness plug, (the plug that you attached to the sensor)
a. measure for continuity to ground on PIN “B” (Ohm meter probe on chassis other probe on PIN “B”)
i. continuity.
8. Pax side sensor chassis harness plug, (the plug that you attached to the sensor)
a. measure for continuity to ground on PIN “B” (Ohm meter probe on chassis other probe on PIN “B”)
i. continuity.
9. Check the left and right sensor’s power signals/chassis wiring run to the PCM.
10. Key in RUN position to send power down the lines to the sensor plugs.
11. Drivers side sensor chassis harness plug, (the plug that you attached to the sensor)
a. measure for power to ground on PIN “C” (volt meter probe on chassis ground other probe on PIN “C”)
i. no voltage, this seems to be a problem.
12. Pax side sensor chassis harness plug, (the plug that you attached to the sensor)
a. measure for continuity to ground on PIN “C” (volt meter probe on chassis ground other probe on PIN “C”
i. 5.0v dc
Other observations, I check the wiring in the driver’s side fuel pump, everything checks out.
The fuel sensor outputs 40.7 to 250 ohms resistance and everywhere in between as you sweep the arms.
The passenger side plug has four pins on the pump and only three pins(fourth is not used) on the harness plug, issue?

TheProsecutor

Also the grounding point on the passenger/right rear grounding point has NO wires attached.

I re-seated all the plugs and checked for proper connections, ie I get what I am supposed to on the yellow plug. The wiring is correct etc.

On the yellow plug, it appears that pin a and pin d are both grounded.

Yes, the left and right sensor signal values are changing, in the correct direction when compared to the fuel table in your previous post.
250 ohms when full and 40.7 when empty.

Bill Curlee

The passengers side rear fender well G-402 is only used on 97-early 98 Rea mounted EBTCM Cars.. Yours should be capped with a rubber plug and not used.

BC

69

After reviewing this thread, I note your statement for the drivers side (L/H) sensor that you get the following;
a. measure for power to ground on PIN “C” (volt meter probe on chassis ground other probe on PIN “C”)
i. no voltage, this seems to be a problem.

I agree, you should have voltage on this line/wire with the key placed in the "run" position.
Way Forward;
WARNING for this test the negative batter cable MUST BE DISCONNECTED FROM THE BATTERY!!!!

Lift the right front of the car, remove the right front tire to gain access to the PCM> Remove the wheel liner access panel to expose the PCM.

Remove connecter "C2" from the PCM and inspect the PCM and PCM Connector for corrosion. For this inspection, you need to focus on "C2" wire pin number "54".

Checking the wire run form the PCM C2 pin "54" to the drivers side (L/H) sensor Yellow connector Pin "C" perform the following;

To determine if the wire is shorted to the chasse from the PCM to the sensor
1) Remove connecter "C2" from the PCM.
2) Remove (L/H) sensor Yellow connector.
3) Checking continuity of the wire running from the PCM to the sensor, Place OHM Meter on Pin "C" of the yellow connector and chasse ground. (Result should be OPEN>NO Continuity. Post your result.

Next> to determine if the wire is not broken from the PCM to the sensor.

4)Place jumper wire on the yellow connector Pin "C" , connect to chasse ground.
5)WARNING BE CAREFUL NOT TO DAMAGE THE C2 PIN 54 On this step!
Place OHM Meter on PCM wire harness Connector "C2" PIN 54 and chasse ground (Result should be Continuity >NOT OPEN. Post results.
.
If the wire passes both the above tests, Perform detailed visual inspection of the PCM and C2 plug.
Using electrical contact cleaner spray, thoroughly spray the C2 plug to clean the connector pins.
Reconnect the C2 Plug to the PCM, reconnect the Yellow sensor plug, reconnect battery, place key to the run position and see if the fuel gauge comes back to life.
Post up your results.

Goose

TheProsecutor

Thanks Goose,

I will try that this Sunday. I appreciate the help.