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I have an 08 Cobalt LT and it is pulling code P0463. Car wont start and isn't receiving fuel. I have checked fuses and relay, dropped the tank and put power to the fuel pump and it runs as I just put a new one in less than a year ago. My son told me that the gas gauge was acting up and when the car wouldn't start it said it had zero gas even though it had a full tank when the key was on. the next day I went to work on it and the gas gauge was working saying it had 7/8 of a tank

I feel this could be an electrical issue but what I'm not finding is a ground wire back near the gas tank. Does anyone know where I could find the ground wire or if anyone has had a similar issue '

this is also a California emissions car
 

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When the gauge reads zero fuel do you also get the low fuel message?

---------- Post added at 04:02 PM ---------- Previous post was at 03:52 PM ----------

P0463
1. Fuel Gage Inaccurate or Inoperative


Circuit/System Description
The fuel level sensor changes resistance in response to the fuel level. The engine control module (ECM)/powertrain control module (PCM) monitors the signal circuit of the fuel level sensor in order to determine the fuel level. When the fuel tank is full, the fuel level sensor resistance is low and the ECM/PCM senses a low signal voltage. When the fuel tank is empty, the fuel level sensor resistance is high and the ECM/PCM senses a high signal voltage. The ECM/PCM uses the signal circuit of the fuel level sensor in order to calculate the percentage of fuel remaining in the tank. The ECM/PCM sends the fuel level information via the serial data circuit to the body control module (BCM). The BCM sends the fuel information to the instrument panel cluster via the serial data circuit in order to control the fuel gage and display the fuel level.

Conditions for Running the DTC
• The ignition is ON, with the engine running.

• The system voltage is between 9-16 volts.

Conditions for Setting the DTC
• The sensor output is greater than 2.9 volts.

• The above condition is present for greater than 30 seconds.

Action Taken When the DTC Sets
• The fuel gage defaults to empty.

• The low fuel indicator illuminates.

• The ECM/PCM records the operating conditions at the time that the diagnostic test fails. The ECM/PCM displays the failure information in the Failure Records on the scan tool.

Conditions for Clearing the DTC
• The DTC becomes history when the conditions for setting the DTC are no longer present.

• The history DTC clears after 40 malfunction-free warm-up cycles.

Reference Information
Schematic Reference
Instrument Cluster Schematics

Connector End View Reference
Component Connector End Views

Description and Operation
Instrument Cluster Description and Operation

Electrical Information Reference

• Circuit Testing

• Connector Repairs

• Testing for Intermittent Conditions and Poor Connections

• Wiring Repairs


Scan Tool Reference
Control Module References for scan tool information

Circuit/System Verification
Ignition ON, observe the scan tool Fuel Tank Level Remaining parameter. The reading should be between 4 percent and 98 percent.

Circuit/System Testing
Ignition OFF, disconnect the harness connector at the fuel level sensor.
Ignition OFF, test for less than 1 ohm between the low reference circuit terminal D and ground.
⇒ If greater than the specified range, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM/PCM.

Ignition ON, install a 3A fused jumper wire between the signal circuit terminal C and the low reference circuit terminal D. Verify the scan tool Fuel Tank Level Remaining parameter is greater than 98 percent.
⇒ If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit test normal, replace the ECM/PCM.

If all circuits test normal, perform the fuel level sensor component test before replacing the fuel level sensor.
Component Testing
Ignition OFF, remove the fuel level sensor.
While sweeping the fuel level sensor through its full range of motion, test for a minimum value less than 41 ohms and a maximum value greater than 119 ohms between signal terminal C and the low reference terminal D.
⇒ If not within the specified range, replace the fuel level sensor.

Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• Fuel Level Sensor Replacement

for the 2.4L engine

• Fuel Level Sensor Replacement for the 2.2L engine

• Fuel Level Sensor Replacement for the 2.0L engine

• Control Module References

---------- Post added at 04:18 PM ---------- Previous post was at 04:02 PM ----------



Chances are it isn't the ground since all your tail lights wouldn't work or do they?

Ground 402


---------- Post added at 04:30 PM ---------- Previous post was at 04:18 PM ----------

Ground lug 402 is (CKT 850) Center of the rear shelf near the right rear speaker
 

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Discussion Starter #4
at first when the gas gauge read zero I did get the low fuel message but now the gauge shows 7/8 of a tank which seems accurate

I will check the ground and if my tail lights are working but how do
I test this if
a) my car doesn't start
b) I have the fuel tank removed from the car

Thanks for responding
 
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