Indicator Glows, Engine Hard to Start

1. Check current draw of each glow plug. Test by attaching ammeter to each glow plug in turn and turning ignition switch to position "2". After 10 to 20 seconds, the current draw of each glow plug should be between 8 and 15 amps. If the reading is ok, then glow plug system is good. If the system fails this step, proceed as follows:
a. If reading is above 15 amps replace the glow plug.
b. If the reading is below 8 amps check wiring and glow plugs for continuity with an ohmmeter. Repair or replace parts as necessary.




NOTE:
It is possible, due to unfavorable tolerances, that the indicator lamp will indicate a faulty glow plug only after 2 glow plugs in cylinders 2 to 4 (four cylinder engines) or cylinders 2 to 5 (five cylinder engines) have failed.
To ensure that the failure indication circuit is operating properly, disconnect 2 glow plug leads of cylinders 2 to 5 and retest preglow system.
If the preglow indicator lamp indicates a fault (does not light up), the preglow time relay is operating properly.