Patrol 4x4 - Nissan Patrol Forum banner

1 - 3 of 3 Posts

·
Registered
nissan
Joined
·
7 Posts
Discussion Starter · #1 ·
Hi folks. Here's my problem.
Vehicle is GQ 2.8 1995. Meter Back L fuse keeps blowing. Just started the day I did the timing belt. Previously no issues at all.
I've read heaps of posts on this site and others about this problem. Looks like a lot if potential causes. I started by checking temp sender and any wiring near the front of the engine where I'd been working. Then started pulling plugs and wires off things one by one and checking the fuse. Burnt out about twenty fuses in the process!!
But I've narrowed it down to the glow plug circuit No2.
If I disconnect the lead that goes to the short glow plug rail all is good (except cold starting).
As soon as I plug those rear three glow plugs in it pops the fuse. Not always instantly and a couple of times I've driven quite a while before it goes. But it always goes either when I switch off or on (don't know which) but not while motoring.
What's got me beat is this - it's the after glow circuit that is obviously at fault (it's the number two relay) but why is the car hard to start when this circuit is not connected. I'd have thought that it would start easily enough on the pre-glow but perhaps run rough for a while with no after glow?
And I'm also stumped as to what the problem might be. Looking at the circuit it appears that the only way this fuse could be blowing on this glow circuit is if the power feed to this relay is being grounded on the hot side. It appears that the glow controller switches the relay to earth so obviously an earth fault on the negative side of this relay would just hold on the after glow circuit wouldn't it? I've checked all I can and traced the wires but can't see a problem.
I'm seriously considering deleting this relay and manually switching it if I need it it all.
But before I do, if anyone can shed any light on this, then I'd like to try and keep it operational.
However if it must go, then I have a couple of further questions. I've read all about the 4.2 glow plug conversion, but why would you have to use 4.2 glow plugs. Why not use the 2.8 glowies and just manually switch them? Is it just that the 4.2's are cheaper?
And if I was doing a manual switch job, why not incorporate a timer that keeps the plugs glowing for a little while after ignition? Or is there really no need?
 

·
Registered
nissan
Joined
·
44 Posts
I can't help too much on what exactly is blowing your fuse, but maybe some information on the system and how to convert to manual will help.

The system uses two relays and two types of glow plugs. The single contact plugs ground through the head. The dual contact plugs ground through the second rail and are used as a voltage reducer by adding resistance to the circuit and pulling everything down to around 6.5 volts. Additionally the factory plugs are ceramic and need to be treated carefully (don't overtorque the top contact nuts and don't run them hot for too long). The reason you need different plugs is that if you switch manual you should be converting to a simpler 12 volt system and forget the voltage sink system and then you only need one relay.

In my case the electrics were shot in the Patrol when I bought it, so even the temp sensor wasn't working right further screwing up the system. Once you identify the two relays involved you can disconnect the one for the short rail completely then use the plug to wire up your switch. Check the wires and wiring diagram carefully to get the leads right. As for glow plugs, you can use anything that has the same dimensions and runs on around 11.5 volts. I'm using CP-05 if I recall correctly (used in a Mitsubishi diesel if I recall correctly). Takes about 6 seconds to heat and start. I just walked around the parts bazaar here with an original and a caliper comparing the physical dimensions of various plugs until I found what I wanted.
 

·
Premium Member
nissan
Joined
·
2,288 Posts
Check your reverse light and trailer plug for damage, that's the normal cause of that fuse blowing.
 
1 - 3 of 3 Posts
Top