Preliminary Diagnosis

Glow plug system preliminary diagnosis should be performed only after ensuring that glow plug system is correctly installed. Check that all connectors are properly installed and that all connections are clean and tight.

This procedure is used to determine if a problem exists in the glow plug system itself, or elsewhere in the electrical system. This procedure should always be completed before performing ELECTRICAL SYSTEM DIAGNOSIS .

1. Connect ammeter in series (an induction type meter may be used) with Red or Orange wire leading from top of controller to left bank of glow plugs. If using an in-line ammeter read both banks at once. DO NOT  cut wire.
2. Operate system and note ammeter reading. Repeat procedure for right bank of glow plugs. On pickups, reading must be at least 55 amps. On vans, reading must be at least 50 amps.
3. If ammeter reading is correct, glow plug system is operating correctly. If ammeter reading is less than specified, one or more glow plugs is inoperative. Go to next step.
4. Check individual glow plug leads by connecting ammeter in series with Green wire that feeds glow plug. Operate system and note ammeter reading. Repeat procedure for each glow plug.
5. On pickups, each individual wire should have a reading of about 14 amps. On vans, reading is about 13 amps. If ammeter readings are correct, glow plugs and harness are okay. Problem is elsewhere. If readings are less than normal, go to next step.
6. On those glow plugs with less than normal readings, check for continuity through harness by disconnecting glow plug lead and connecting a 12-volt test light from connector to ground. Operate glow plug system.
7. If test light glows, harness is okay. Replace glow plug(s). If test light does not glow, repair or replace harness. Retest glow plug(s) for proper operation.