D. With Key Start System (Model 115.1)

Checking Preglow System

Conventional tools
Voltmeter (measuring range 0-3 volts/0-16 volts)
Ammeter (measuring range 0-60 amps)

Note
Battery charged mm 60 % (acid density approx. 1.22 g/cc).

D. With key start system engine 617 in model 115.1

a) Preglow system not preglowing

This complaint is the result of an interruption in circuit of preglow system.




Adjust voltmeter to measuring range 0-16 volts. Connect plus cable of voltmeter to input of glow plug of 5th cylinder and connect minus cable to ground. Turn key on steering ock starter switch to position "2" and read voltage on voltmeter.

If voltmeter indicates 12 volts, look for interruption on glow plugs or their connections.

If voltmeter indicates 0 volt, look for interruption at preglow time relay or its connections.




1. Checking glow plugs for interruption
Connect minus cable of voltmeter to ground. Check voltage with plus cable of voltmeter at current input and output of the five glow plugs.

If 12 volts are measured at current input of a glow plug and 0 volt at output, this glow plug is interrupted and must be replaced.




2. Checking preg lowing time relay and its connection
Turn key of steering lock starter switch to position"2".

Pull coupler from preglow time relay. Connect minus cable of voltmeter to socket 1 of coupler. Check socket 5 and 4 one after the other with plus cable of voltmeter. If voltmeter indicates each time 12 volts, replace preglow time relay.




If voltmeter indicates 0 volt, connect minus cable of voltmeter to ground. Check at socket 5 of volt- meter with test cable.

If voltmeter indicates 12 volts, line 31 to socket 1 is interrupted.

If voltmeter indicates 0 volt, line 30 to socket 5 is interrupted.




Then check socket 4 with plus cable of voltmeter.

If voltmeter indicates 0 volt, line 15 to socket 4 is interrupted.

In the event of complaints, check lines or connections for a loose contact.

b) Preglow system preglows too slowly or too fast




Nominal time at: +20 °C approx. 12 seconds
- 5 °C approx. 30 seconds

This complaint is caused bv insufficient current flowing through preglow system as a result of transfer resistances or too much current as the result of a short-circuit.




Measure glow current with ammeter first. For this purpose, connect ammeter to connection of glow plug for cylinder 5.

Glow current in preglow position: 50-55 amps.

Measured after approx. 15 seconds (battery charged at least 60%).

If this glow current is not attained, measure voltage drop in preglow system with voltmeter.

Check connections for tight seat.





Attention!
When checking the voltage, connections of glow plugs, as well as the resistance conductors may not be shorted against ground (screwdriver against engine block), since this may lead to failure of preglow time relay.

If this glow current is exceeded, a short-circuit on preglow system is indicated.

If one of the glow plugs is lost by a short-circuit, change glow plug and measure preglow current once again.

c) Preg low system glows, preg low indicator lamp not indicating

1. Check line from glow plug cylinder 5 to preglow indicator for interruption.

2. Check bulb of preglow indicator lamp in instrument cluster (pay attention to tight seat of bulb in socket).