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MD22 glow light always on

1

123rolle

New member
I have an old MD22 motor and the glow lights stay on always when the battery is connected even if key is not switched on. Any ideas what this can cause and how to solve it? Where are the glow plugs located? Does anyone have image of the placement or explode chart that shows it?
 
The lamp glows because current is flowing thru it...likely due to a set of contacts that are closed that shouldn't be... another possibility is damaged wiring ...

One usually troubleshoots the circuit, finding a bad component, and replacing it...

The glow plugs typically mount to the cylinder head.
 
I found the diodes being fine on the instrument panel and fuses are also fine. Cannot find any place where the wiring is broken or current could be floating to the glow light. Any ideas?
 
The glow plug should be on the cylinder head.

Based on your description, the GLOW PLUG lamp glows at the same brightness independently of the KEY switch position?

If yes, can you disconnect the ORANGE wire from the key switch and see what happens to the GLOW PLUG lamp?
 
I removed orange wire first from diode in key switch. Nothing changes. Then taped over the connection of orange wire under the key switch cables and still the glow light stays on same brightness.
 
Ok...that suggests the key switch and wiring are functional and the issue is either in the alarm unit or the glow plug relay has fail (contacts arced over). I would reconnect the orange wire and then locate the glow plug relay and remove it from the socket and see what happens then.

not sure about "diode in the key switch"...that suggests you have more than one control panel - is that the case?
 
I have removed orange wire from the relay also but nothing happens. Only one control panel. The orange wire goes in the key switch and leaves as orange to diode which is wired to another diodes.
 
This may help - straight out of the operations manual...:

4. Warning display
The display has four “windows”. If the acoustic alarm
comes on, one of windows “A -C” starts to blink (red)
to show the cause of the alarm.
A. Coolant too hot. Reduce the speed to idling (in
neutral) until the temperature decreases.
Investigate the cause of the alarm (e.g. restricted
water supply to the engine). Stop the engine if
the temperature does not decrease.
B. Lubricating oil pressure too low. Stop the engine
immediately and locate the cause of the alarm.
C. Alternator not charging.
D. Pre-heating (indicator lamp comes on when glow
plugs are on).
NB. This lamp also works as a filament guard for
the glow plugs. This will also be lit when the key
switch is in position I (operating position) if there is
a fault in the system (break).

The fault could be the relay (contacts corroded/burnt) as well as a bad wire/connection in the glow plug circuit.
 
I tested the relays with multimeter and those seem to be fine. There was one yellow cable burnt but don't know where the other end was supposed to be because it had been burnt through the connector so it was loose. I think it might be connected to the alternator or to the black wire coming from the battery but not sure.
 
FWIW, the glow plugs will draw a helluva lot more current than you can imitate using a multimeter testing for continuity...much better is a test lamp that will draw at least an amp.

I don't see any yellow wires in the schematic - orange is the closest and that appears to be used exclusively for the glow plugs...
 
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