Indicator Does Not Glow, Engine Won't Start

Checking the main power circuit of the preglow system for open circuit.

Problem:
Preglow indicator lamp fails to light up, engine cannot be started.





- With the multimeter in the volt measuring range, check voltage on terminal 30 of the preglow time relay against ground.

- If no voltage is present. check red 4 mm wire from the terminal block X35 terminal 30 to the preglow time relay terminal 30 for open circuit and eliminate open circuit if necessary.

- If voltage is present (approx. 12 V), check 80-A fuse for tight seat or an open circuit, replace if required.





- If no fault was found so far, check voltage on jack 1 of the 4-pin coupling of the preglow time relay against ground

- If no voltage is present with preglow system switched on (model 201), check red/black wire from the central electrical coupling S jack 4 to the coupling jack 1 of the preglow time relay for an open circuit and eliminate open circuit.

- On model 124, check pink/red wire from fuse 7 (unprotected side) via connector engine/interior 12-pole X 26 to coupling jack 1 of the preglow time relay for open circuit and eliminate open circuit.









- If voltage is present (approx. 12 V), connect multimeter in volt measuring range to jack 1 (terminal 15) and jack 4 (terminal 31) and measure voltage (set value approx. 12 V).

- If no voltage is indicated, check brown wire from jack 4 to ground for open circuit and eliminate open circuit.

- If no fault was established to this point, the preglow time relay is defective, replace preglow time relay.