Indicator Glows, Engine Hard to Start

TESTING GLOW PLUGS AND THEIR WIRING

If the following problems occur:

- Preglow indicator lamp does not light up when switching on.
- Lights up for approx. 1 min. when driving.
- Engine is difficult to start.

There may be an open circuit in one or more glow plugs or in the cables to the glow plugs.





Test current consumption of the glow plugs with multimeter set to Amperes range and with D.C. clamp. The clamp is placed over the individual cables at the preglow time relay for the step.

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 key in the steering lock to position "2", the current consumption of each glow plug must be 14-16 A after 10-12 seconds.

- If the reading is higher than 16 A, replace glow plug. If the reading is less than 14 A, test glow plug cable for open circuit.





- Detach 6-pin connector from preglow time relay for testing for open circuit. With the multimeter set to Ohms range, measure in turn the resistance to ground (engine block) at

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 in the lead or the connection. Rectify open circuit in the lead or replace glow plug.

SAFEGUARDING PREGLOW CIRCUIT

An electronic short-circuit safeguard is installed in the preglow time relay. The circuit is interrupted if a short-circuit develops in the glow plugs or in the cables.

THE RELAY IS AGAIN OPERATIONAL

- Once the short-circuit has been rectified and
- The key turned back to position "0".

TESTING TEMPERATURE SENSOR WITH WIRING





Preglow time until preglow indicator lamp goes out is too short or too long (refer to table). Detach plug on preglow time relay and test F resistance to ground F with multimeter set to Ohms range.

Specification:

at +25 °C 2442 ± 170 omhs
at +180 °C 291 ± 16 omhs

- If specified value is achieved:

Replace temperature sensor.

- If resistance infinite ohms is indicated:

Rectify open circuit in cable.

- If resistance < 1 ohms is indicated:

Rectify short-circuit in cable.