Fuel Level Sensor Circuit

280

TM 9-2320-312-24-2

Troubleshooting Section

The fuel level sensors are OEM installed components

H. Activate the "Fast Idle Enabled Lamp" test.

for the vehicle. The sensors are selectable through

Observe the voltage test lamp. The lamp should

a Customer Programmable Parameter and the

turn on when the test is active. Also, the lamp

Customer Programmable Parameter may be

should turn off when the test is inactive.

protected by Customer Passwords.

Expected Result:

The sensors read the level of fuel in the primary fuel

tank and secondary fuel tank. The sensors require

The test lamp turns on and the test lamp turns off

a +5 VDC supply from the ECM. The customer

per the above description.

programmable parameters "Primary Fuel Tank

Size" and "Secondary Fuel Tank Size" must be

Results:

programmed to "25", "35", or "50" for this feature

Yes The ECM is operating correctly. There is a

to work.

problem in the vehicle wiring or the lamp. STOP.

Repair: Temporarily connect a test ECM. Check

the ECM operation of the fast idle lamp when the

test ECM is installed. If the problem is resolved

with the test ECM, reconnect the suspect ECM.

If the problem returns with the suspect ECM,

replace the ECM.

STOP.

i01631206

Fuel Level Sensor Circuit - Test

SMCS Code: 7483-081-NS

System Operation Description:

Use this procedure under the following situation:

This feature is only available on GMT-560

applications.

Use this procedure to troubleshoot the system only

when there is an active diagnostic code or when

a diagnostic code can easily be activated. This

procedure covers open circuit diagnostic codes and

short circuit diagnostic codes that are associated

with the fuel level sensors.

96-03 Primary Fuel Level Sensor Open Circuit (44)

96-04 Primary Fuel Level Sensor Short Circuit (44)

128-03 Secondary Fuel Level Sensor Open Circuit

(44)

128-04 Secondary Fuel Level Sensor Short Circuit

(44)

The following background information is related

to this procedure: