Arno
New Member
- Joined
- Apr 17, 2016
- Messages
- 26
Below a bit about the Super Glow pre-heating system in the LJ70.
Bottom line; my LJ70 has a short circuit somewhere in the glow-plug system.
My question: Any hints in finding a short-circuit?
Her's the runnup of events with a few interesting facts;
Recently, with the weather getting colder, i discovered the glow-plug in my LJ70 didn't work at all.
With the symptoms of a longer crank in the morning, i had a look after the symptoms stayed.
Normally my Lj70 lives in 20+ Celsius weather, so not much to do for the glowplugs most of the year
Here's what i did;
1) I check if there was any voltage on the glowplug railing connecting all glow plugs : Nothing
2) Then i checked if the main relay if it send a voltage out : It did
3) Measured the wiring from the relay to the glowplug railing : No connection, so wiring issue?
Here's what i found;
After some measurements in different wiring section I found there was a disconnect inside the connecter straight after the main relay. (28610 - 54280)
Looking side I initially saw nothing, these waterproof connector don't show much from the outside.
Tampering with the wiring inside the connecter showed one of the connector rods was fully loose, just came out when i pulled it with a pliers.
It looked like it was melted / burned away - the wire itself is quite thick, hard to break.
With the current running through the connecter, my initial thought was a freak manufacturing issue years ago.
What I changed / repaired;
Decided to replace the connector with wiring of enough thickness - removing the original connector altogether.
Then this happened;
On the first glow attempt the wiring at the + PLUS of the battery started melting - smoke came from the wires!
So way too much current in already thick wiring -this is very very wrong.
Here I stopped, there's a short circuit somewhere in the glowplug system.
From here I had a look at the wiring diagram of the Super Glow system in the LJ70 (year 90 - 95)
It seems pretty simple, 2 relays, 1 resistor in the manifold and the glowplugs.
The wiring seems original without signs of tampering, the pre-heating timer works
Looking back;
The glow plug system worked definitely last winter - no doubt about it. Had a few -10 Celsius starts.
I recall the voltage meter always dropping down a bit as well during the glow period.
Since last winter the stem valve seals have been changed, which was quite an operation.
Also in this operation the glow plugs where checked - they all seemed ok.
So since the stem valve operation, something must have changed - but no clue where to look.
I checked the railing of the glow plugs which does not seem to touch anywhere.
The glowplug resistor seems ok and wired correctly.
Any idea's where to look for this short circuit?
Obviously, the connector was the weakest link and burned out because of the short circuit.
Cheers!
Arno
Bottom line; my LJ70 has a short circuit somewhere in the glow-plug system.
My question: Any hints in finding a short-circuit?
Her's the runnup of events with a few interesting facts;
Recently, with the weather getting colder, i discovered the glow-plug in my LJ70 didn't work at all.
With the symptoms of a longer crank in the morning, i had a look after the symptoms stayed.
Normally my Lj70 lives in 20+ Celsius weather, so not much to do for the glowplugs most of the year
Here's what i did;
1) I check if there was any voltage on the glowplug railing connecting all glow plugs : Nothing
2) Then i checked if the main relay if it send a voltage out : It did
3) Measured the wiring from the relay to the glowplug railing : No connection, so wiring issue?
Here's what i found;
After some measurements in different wiring section I found there was a disconnect inside the connecter straight after the main relay. (28610 - 54280)
Looking side I initially saw nothing, these waterproof connector don't show much from the outside.
Tampering with the wiring inside the connecter showed one of the connector rods was fully loose, just came out when i pulled it with a pliers.
It looked like it was melted / burned away - the wire itself is quite thick, hard to break.
With the current running through the connecter, my initial thought was a freak manufacturing issue years ago.
What I changed / repaired;
Decided to replace the connector with wiring of enough thickness - removing the original connector altogether.
Then this happened;
On the first glow attempt the wiring at the + PLUS of the battery started melting - smoke came from the wires!
So way too much current in already thick wiring -this is very very wrong.
Here I stopped, there's a short circuit somewhere in the glowplug system.
From here I had a look at the wiring diagram of the Super Glow system in the LJ70 (year 90 - 95)
It seems pretty simple, 2 relays, 1 resistor in the manifold and the glowplugs.
The wiring seems original without signs of tampering, the pre-heating timer works
Looking back;
The glow plug system worked definitely last winter - no doubt about it. Had a few -10 Celsius starts.
I recall the voltage meter always dropping down a bit as well during the glow period.
Since last winter the stem valve seals have been changed, which was quite an operation.
Also in this operation the glow plugs where checked - they all seemed ok.
So since the stem valve operation, something must have changed - but no clue where to look.
I checked the railing of the glow plugs which does not seem to touch anywhere.
The glowplug resistor seems ok and wired correctly.
Any idea's where to look for this short circuit?
Obviously, the connector was the weakest link and burned out because of the short circuit.
Cheers!
Arno