TROUBLE SHOOTING
Note. See TROUBLE SHOOTING article in GENERAL TROUBLE SHOOTING.
PRELIMINARY INSPECTION
Check generator wiring harness connections and drive belt tension. Ensure battery is fully charged and connections at battery cables, generator and main fuses are okay. Replace fuse as necessary.
GENERATOR CONTROL SYSTEM TEST
Note. Ensure Electrical Load Detector (ELD) system related DTC(s) do not exist. Diagnose DTC(s) first, if present. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
- Turn ignition off. Disconnect 4-pin generator harness connector. Start engine and turn on headlights (high beam). Check voltage between generator harness connector terminal No. 2 (White/Green wire) and battery positive terminal. If voltage reading is one volt or less, go to next step. If voltage reading is not one volt or less, go to step 3 .
- Turn ignition and headlights off. Disconnect ECM 31-pin harness connector. Check continuity of White/Green wire between ECM harness connector terminal No. 2 and generator harness connector terminal No. 2. See «WIRING DIAGRAMS»(ref-4242-S08062819682000061600000) . If continuity exists, perform «GENERATOR/REGULATOR TEST»(ref-4242-S11530987532000061600000) . If continuity does not exist, repair open in White/Green wire between generator and ECM.
- Turn ignition and headlights off. Disconnect ECM 31-pin connector. Check continuity between ECM harness connector terminal No. 2 (White/Green wire) and ground. If continuity does not exist, replace ECM with a known-good unit and repeat step 1 . If continuity exists, repair short in White/Green wire between generator and ECM.
GENERATOR/REGULATOR TEST
| CAUTION | When performing full field test on generator, charging voltage will increase quickly. DO NOT allow voltage to increase greater than 18 volts, or electrical system will be damaged. |
- Ensure battery is fully charged. Connect Generator Tester (Sun VAT-40). Set tester selector switch to position No. 1 (starting). Place transmission in Park (A/T) or Neutral (M/T). Ensure all accessories are off. Start engine. Operate engine at 3000 RPM until cooling fan comes on, then return to idle. Raise and hold engine speed to 2000 RPM. Check voltage reading on tester. If voltage reading is greater than 15.1 volts, replace voltage regulator. If voltage reading is 15.1 volts or less, go to next step.
- Let engine idle. Ensure all accessories are off. Turn tester selector switch to position No. 2 (charging). Remove tester's inductive pick-up and zero ammeter. Place inductive pick-up on battery ground cable with arrow pointing towards battery negative terminal. Raise and hold engine speed to 2000 RPM. If voltage reading is less than 13.5 volts, test and repair generator components. If voltage reading is 13.5 volts or greater, go to next step.
- Apply load using generator tester until battery voltage drops 12.0-13.5 volts. Check amperage reading on tester. If amperage reading is 75 amps or more, charging system is okay. If amperage reading is not as specified, go to next step.
- Maintain engine speed at 2000 RPM. Full field generator using generator tester probe. (Scheme 2) Momentarily switch tester selector to "A" (ground) position. Check amperage reading. If generator output is 75 amps or more, replace voltage regulator. If generator output is not as specified, test and repair generator components.
