Pinpoint Test U: The Reversing Lamps Are Inoperative

WARNING: This page is about a different car, the 2006 Ford F550 Super Duty, 2006 Ford F450 Super Duty, and 2006 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

U1 CHECK THE REVERSING LAMP RELAY
- Key in OFF position.
- Disconnect: Reversing Lamp Relay C2257.
- Carry out the reversing lamp relay component test. Refer to Reversing Lamps for component testing.
- Is the reversing lamp relay OK?
Yes : GO to U2.

No : INSTALL a new reversing lamp relay. TEST the system for normal operation.
U2 CHECK THE REVERSING LAMP RELAY OUTPUT CIRCUITRY
- Connect a fused (15A) jumper wire between the reversing lamp relay C2257-3, harness side and the reversing lamp relay C2257-5, circuit 140 (BK/PK), harness side.
  
  Fig 1: Checking Reversing Lamp Relay Output Circuitry
  Courtesy of FORD MOTOR CO.
- Are the reversing lamps illuminated?
Yes : REMOVE the jumper wire. GO to U4.

No : REMOVE the jumper wire. GO to U3.
U3 CHECK CIRCUIT 140 (BK/PK) FOR AN OPEN
- Disconnect: CJB C270g.
- Measure the resistance between the CJB C270g-1, circuit 140 (BK/PK), harness side and ground.
  
  Fig 2: Checking Circuit 140 (BK/PK) For Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : VERIFY the CJB fuse 8 (15A) is OK. If OK, INSTALL a new CJB. TEST the system for normal operation.

No : REPAIR the circuit. TEST the system for normal operation.
U4 CHECK THE CJB
- Key in ON position.
- Measure the voltage between the reversing lamp relay C2257-1, harness side and ground.
  
  Fig 3: Checking CJB
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
Yes : GO to U5.

No : INSTALL a new CJB. TEST the system for normal operation.

U5 CHECK THE REVERSING LAMP RELAY CONTROL CIRCUIT

Key in OFF position.
Connect: Reversing Lamp Relay C2257.
Disconnect: PCM C175b or C1381b (Automatic Transmission).
Disconnect: Reversing Lamp Switch C169 (Manual Transmission).
Key in ON position.

Measure the voltage between the PCM or reversing lamp switch, harness side and ground as follows:

SPECIAL TOOL(S)

Vehicle Equipment	Component Connector-Pin	Circuit
Automatic transmission with diesel engine	PCM C1381b-3	324 (YE/LG)
Automatic transmission with gasoline engine	PCM C175b-24	324 (YE/LG)
Manual transmission	Reversing lamp switch C169-1	324 (YE/LG)

Is the voltage greater than 10 volts?

Yes : If equipped with a manual transmission, GO to U7.

If equipped with an automatic transmission, GO to U8.

No : GO to U6.

U6 CHECK CIRCUIT 324 (YE/LG) FOR AN OPEN

Key in OFF position.
Disconnect: CJB C270f.

Measure the resistance between the PCM or reversing lamp switch, harness side and the CJB, harness side as follows:

CJB CONNECTOR-PIN CIRCUIT

Vehicle Equipment	Component Connector-Pin	CJB Connector-Pin	Circuit
Automatic transmission with diesel engine	PCM C1381b-3	CJB C270f-8	324 (YE/LG)
Automatic transmission with gasoline engine	PCM C175b-24	CJB C270f-8	324 (YE/LG)
Manual transmission	Reversing lamp switch C169-1	CJB C270f-8	324 (YE/LG)

Is the resistance less than 5 ohms?

Yes : INSTALL a new CJB. CLEAR the DTCs. REPEAT the self-test.

No : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.

U7 CHECK CIRCUIT 57 (BK) FOR AN OPEN
- Key in OFF position.
- Measure the resistance between the reversing lamp switch C169-2, circuit 57 (BK), harness side and ground.
  
  Fig 4: Checking Circuit 57 (BK) For Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : INSTALL a new reversing lamp switch. TEST the system for normal operation.

No : REPAIR the circuit. TEST the system for normal operation.
U8 CHECK FOR CORRECT PCM OPERATION
- Disconnect all the PCM connectors.
- Check for:
  - corrosion
  - pushed-out pins
- Connect all the PCM connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes : INSTALL a new PCM. REFER to ELECTRONIC ENGINE CONTROLS - GASOLINE ENGINES or ELECTRONIC ENGINE CONTROLS - DIESEL ENGINE . TEST the system for normal operation.

No : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.