Indicator Glows, Engine Hard to Start

TESTING GLOW LAMP AND WIRING

If the following complaint is received:
Preglow indicator lamp does not light up, engine does not start easily, there may be an open circuit in one or more glow plugs or of the cables to the glow plugs.

If the following problem arises:
Preglow indicator lamp lights up when ready to start condition is reached; however, engine does not start easily. There may be an open circuit in a glow plug or in one of the cables to the glow plugs of cylinders 2-5, or the cause may be incorrect current consumption of the glow plugs in cylinders 1-6.





- Using the multimeter Ampere range and the D.C. clamp, test the current consumption of the glow plugs. This is done by placing the clamp over the individual cables at the preglow time relay.

Cylinder 1 = 2.5 black/blue
Cylinder 2 = 2.5 black/violet
Cylinder 3 = 2.5 black/red
Cylinder 4 = 2.5 black/yellow
Cylinder 5 = 2.5 black/green
Cylinder 6 = 2.5 black/white

- Turn the key in the steering lock to position "2"; the current consumption of each glow plug must be 8-15 A after 10-20 seconds.

- If the reading is higher than 15 A, replace the glow plug. If the reading is less than 8 A, test electric cable or plug for open circuit.

- Detach the 6-pin connector from the preglow time relay for testing for open circuit.





- With the multimeter set to the Ohms range, measure in turn the resistance to ground (engine block) as follows:

1 Connector = glow plug cylinder 1
2 Connector = glow plug cylinder 2
3 Connector = glow plug cylinder 3
4 Connector = glow plug cylinder 4
5 Connector = glow plug cylinder 5
6 Connector = glow plug cylinder 6

- If infinite resistance is measured, there is an open circuit in the respective glow plug or at the lead or connection. Rectify open circuit in the lead or replace glow plug.

Note It is possible that the indicator lamp does not indicate a fault (because of unfavorable tolerances) until 2 glow plugs in cylinders 2-5 have failed.

- To check that the fault indication in the preglow time relay is not defective, 2 glow plugs of cylinders 2-6 should be terminated in this case and the preglow operation repeated. Additionally, on Engine 603, test the fault indication of No.6 cylinder. This is done by terminating only the grow plug of No.6 cylinder. If the indicator lamp now shows a fault (does not light up), the preglow time relay is in working order.