Initial Inspection (Visual Inspection)

A visual inspection for loose, disconnected, damaged, or improperly routed wires and hoses should be made before attempting to diagnose the fuel injection system. A visual check will help spot these faults and save unnecessary test and diagnostic time. A thorough visual inspection includes:

1. Check battery cable connections and battery condition (clean, properly charged, etc.).

Engine Control Unit Ground:

2. Check engine control system ground connections on side of frame rail between the air cleaner and the battery.

Relay Location/Identification:

3. Check all engine control system relays for good connections and proper seating. Also check relays for physical damage and corrosion.
4. Check primary and secondary ignition leads for proper connections, routing and condition.
5. Check the air intake for restrictions (dirty air filter).

Component Loctions:

6. Check the Thermal Vacuum Switch (TVS) vacuum lines for proper routing, condition, and connections at the air cleaner.
7. Check the EGR vacuum and electrical leads for proper routing, connections, and condition.
8. Check the speed control vacuum lines for proper routing, condition and connections.
9. Check the power brake booster hose connections and condition.
10. Check the pre-heated air tube condition and connections at the air cleaner and exhaust heat stove.
11. Check the air cleaner air inlet for restrictions and check the hot air valve motor for proper operation.
12. Check the CrankCase Ventilation (CCV) hoses for proper condition and connections.

Throttle Position Sensor And Idle Speed Regulator:

13. Check the Throttle Position Sensor (TPS) and Idle Speed Regulator (ISR) electrical leads for proper routing, connections and condition.
14. Check the ISR hoses for proper condition and connections.

Manifold Absolute Pressure Sensor And Engine Harness Connector:

15. Check the engine harness connectors for proper connections.
16. Check the Manifold Absolute Pressure (MAP) electrical and vacuum leads for proper routing, condition, and connections.
17. Check the body to engine ground strap for proper condition and connections.

EGR Valve And Transducer:

18. Check the EGR valve and transducer vacuum lines for proper routing, condition and connections. Check the EGR valve and transducer for signs of physical damage or tampering.
19. Check the engine speed sensor (Crankshaft Position Sensor -- CPS) wiring harness for proper routing, condition, and connections.
20. Check the throttle linkage, accelerator cable, cruise control cable, and throttle cable for damage, binding or sticking.
21. Check the throttle return spring for damage or fatigue.
22. Check the primary and secondary ignition leads for proper condition, routing, and connections.
23. Check the fuel injector electrical and fuel connections.
24. Check the fuel pressure regulator vacuum line for wear and/or damage.

Coolant Temperature Sensor:

25. Check the coolant temperature sensor electrical connection.

Cooling Fan Switch:

26. Check the electric cooling fan circuit for proper wire routing and connections.
27. Check the starting system circuit for proper electrical wire routing and connections.
28. Check the fuel pump electrical and fuel line connections.