Pinpoint Test A: No Power in All Ignition Switch Positions

Steering Column Switches

Pinpoint Test A: No Power in All Ignition Switch Positions


Normal Operation

For all vehicles except stripped chassis, the Smart Junction Box (SJB) provides the ignition switch with fused battery voltage through SJB (Smart Junction Box) fuse 27 (20A) along circuit SBP27 (BU/RD). For stripped chassis vehicles, the Battery Junction Box (BJB) provides the ignition switch with fused battery voltage through BJB (Battery Junction Box) fuse 36 (20A) along circuit SBB36 (GN/RD). The ignition switch then provides voltage to the SJB (Smart Junction Box) along several different circuits depending on the ignition switch position. The ignition switch has 4 possible positions:

- OFF- No voltage on any circuit

- ACC- Voltage on circuit CDC33 (VT/GN) to SJB (Smart Junction Box)

- RUN- Voltage on circuit CDC32 (BN/YE) to SJB (Smart Junction Box)
- Voltage on circuit CDC34 (WH/OG) to SJB (Smart Junction Box)

- Voltage on circuit CET53 (BU/OG) to SJB (Smart Junction Box)

- START- Voltage on circuit CDC34 (WH/OG) to SJB (Smart Junction Box)

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors

- Fusible link(s)

- Fuse

- Ignition switch

PINPOINT TEST A : NO POWER IN ALL IGNITION SWITCH POSITIONS

NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multi-meter probes.

NOTE: Verify that the battery voltage is 10 volts or greater.

A1 CHECK FOR VOLTAGE AT THE IGNITION SWITCH FUSE

- Disconnect: SJB (Smart Junction Box) Fuse 27 (20A) (All vehicles except stripped chassis).

- Disconnect: BJB (Battery Junction Box) Fuse 36 (20A) (Stripped chassis vehicles).

- For all vehicles except stripped chassis, measure the voltage between SJB (Smart Junction Box) fuse 27 (20A) input side and ground.

- For stripped chassis vehicles, measure the voltage between BJB (Battery Junction Box) fuse 36 (20A) input side and ground.

Is the voltage greater than 10 volts?

Yes
GO to A2.

No
VERIFY fusible link(s) A (8 gauge, RD) and C (10 gauge, RD) are OK. If OK, REPAIR circuit SDF05 (RD) or SDF01 (RD) for an open. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short Electrical Diagrams. TEST the system for normal operation.

A2 CHECK THE VOLTAGE TO THE IGNITION SWITCH

- Connect: SJB (Smart Junction Box) Fuse 27 (20A) (All vehicles except stripped chassis).

- Connect: BJB (Battery Junction Box) Fuse 36 (20A) (Stripped chassis vehicles).

- Ignition OFF.

- Disconnect: Ignition Switch C250.

- For all vehicles except stripped chassis, measure the voltage between ground and:
- ignition switch C250-2, circuit SBP27 (BU/RD), harness side.

- ignition switch C250-7, circuit SBP27 (BU/RD), harness side.

- ignition switch C250-9, circuit SBP27 (BU/RD), harness side.


- For stripped chassis vehicles, measure the voltage between ground and:
- ignition switch C250-2, circuit SBB36 (GN/RD), harness side.

- ignition switch C250-7, circuit SBB36 (GN/RD), harness side.

- ignition switch C250-9, circuit SBB36 (GN/RD), harness side.






Are the voltages greater than 10 volts?

Yes
INSTALL a new ignition switch. REFER to Ignition Switch Service and Repair.

No
REPAIR the affected circuit(s). TEST the system for normal operation.