Glow plug black/yellow stripe wire on relay has timed 12V but no voltage at the glow plugs

[Sandy Landy]

Hi Mates,
Hope all is well. I bought a 97 Defender 130 which is in fairly great shape from the first owner, it needs some TLC which I am giving it.

I noticed that it's hard starting a bit on the first start of the day and though the glow light is working, I am not getting power to the glow plug harness.  The odd thing is, I am getting the timed 12V output from the relay output on the black/yellow stripe wire but yet no power is going to the glow plugs. I am not getting continuity between the the relay BL/Yel output wire to the glow plug harness, there is an open circuit somewhere.

The 60 amp fuse in the engine bay is Ok too and so is fuse # 17 in the fuse box inside. Is the wire from the relay connected directly to the glow plugs or is there another fuse somewhere, fuse link? I cant trace it easily since it going to the harness junction in the center of the bulkhead with a plastic cover over it, so was wondering if you guys knew if it was a straight run from the relay to the glow plugs or not.

I read that the 60 amp fuse and a 15 amp fuse #17 is within the circuit, but I don't think they are causing any issues because I am getting the 12V out put from the relay but nothing at the glow plugs. I have to clean the engine and chassis grounds too to see if that help with the hard starting when cool. 

The size of the wire on the glow plug relay is of a bigger gauge than that of the black/yellow stripe on the glow plugs, which makes me believe there is a connection somewhere between these too. 

Cheers and thanks.

 

[western]

The Thick yellow/black from timer should be connected to the number 4 glowplugs nearest the bulkhead, if it is connected & no power at the 4 glowplugs then there must be a break in the wire. 

[miketomcat]

If your getting power at the relay but not the plugs I would suggest the wire from the relay to plugs is broken or has a bad connection. Failing that check the link wires and the engine earth. When you test are you using the engine block for the neg or something else? 

Mike

[Sandy Landy]

4 hours ago, western said:

The Thick yellow/black from timer should be connected to the number 4 glowplugs nearest the bulkhead, if it is connected & no power at the 4 glowplugs then there must be a break in the wire. 

Hi western, looking at the schematic where I have the red arrow, does indicate its a straight connection from the relay but I cant possibly understand how such a heavy gauge wire can be broken where its secure along the bulkhead. I hate doing any bypassing of any sort unless I really have to, so I might pull apart the harness along the bulkhead and trace it to see where its broken.  

Thanks for your reply. I also have two relays and a relay socket I will post pics of for help identifying their usage.

 

Cheers Mate.

[Sandy Landy]

4 hours ago, miketomcat said:

If your getting power at the relay but not the plugs I would suggest the wire from the relay to plugs is broken or has a bad connection. Failing that check the link wires and the engine earth. When you test are you using the engine block for the neg or something else? 

Mike

Hi Mike, I will trace it. I am using the engine for ground. The starter seems like it's turning over a bit slower so I will check the grounds/earths and clean them up too, but that should not cause the issue I am having with the glow plugs.

 

Cheers and thanks.

[western]

This is the glowplugs relay terminals & 200tdi engine loom diagram, its not that much different from the 300tdi 

 

[Sandy Landy]

Thanks Western, I will do some tracing and will update my findings here Mate.

Thanks so much again, you are knowledgeable and always helpful.

Cheers. 

[Peaklander]

Hi. Here’s a screengrab of a late 300TDi diagram. It shows that there’s no connector between the glow plug relay and #4 cylinder plug. It is a straight through cable.

You can also see that the return to battery negative is through the engine block and so need to ensure that there is a connection from there to chassis and onto the battery negative. 

Edit: I have now read that you have already seen this. Oh well I’ll leave it here anyway.

Edited May 5, 2022 by Peaklander

[Sandy Landy]

6 hours ago, Peaklander said:

Hi. Here’s a screengrab of a late 300TDi diagram. It shows that there’s no connector between the glow plug relay and #4 cylinder plug. It is a straight through cable.

You can also see that the return to battery negative is through the engine block and so need to ensure that there is a connection from there to chassis and onto the battery negative. 

Edit: I have now read that you have already seen this. Oh well I’ll leave it here anyway.

 

Hi Peaklander,

Thanks for the reply. The battery negative to the chassis and transfer case ground stud were all intact, however upon inspection, I realized that the tab to the chassis which was soldered to the cable was completely loose, thought it was crimped but it was not. I cleaned the connection and soldered it again, then I discovered that the negative battery terminal had a huge crack in it and I changed that too. I cleaned all the mounting points and reassembled everything but the first start is still sluggish, after that it cranks over fast.

I will do a load test on the battery tomorrow and then do a voltage drop test between the battery and the positive terminal on the starter. I did a load test and a charge test on it a few months ago and it was fine, the battery was bought new last March. I still have to trace the glow plug wire tomorrow too, though I am in the tropics I would still like to have that working, it will still be of use on first start up of the day.

Cheers Mates and thanks for all the help, you guys are great.

 

[Sandy Landy]

Well Mates, the simple things makes you want to smack yourself 

The whole glow plug issue was a loose connection at the #4 glow plug terminal. My Landy has a 3 inch lift so looking at the #4 glow plug is difficult from the fender side, especially with the air filter housing blocking view and access. So I was testing for voltage at the #1 plug all the time and since I had continuity between there and the #4 terminal I figured it was an ok test point. 

I decided to jump up on the bumper  to get to the connection and look at the feed wire only to discover, that it's a bigger gauge from the relay and two, it was loose.

Seeing the relay wire having a bigger gauge than that of the glow plug harness lead me to believe it was spliced somewhere but in actual fact, the bigger gauge was connected to the #4 glow plug terminal and harness. So now I am getting power to the plugs. The relay only stays on for like 3 seconds but it's hot here right now.

Thanks for all the replies and help Mates.

[western]

Glad you found the fault & est of all a no expense fix 

[Sandy Landy]

Indeed Western. Thanks so much for your help. I might have some other quires later on about some other non related connections, if I cant figure them out. I also have some pics to post regarding the ground cable showing how you cant take a lot of things for granted.

Thanks so much Mate and have a good night, will its almost 3AM there, almost 10PM here 

[Sandy Landy]

Good Day Mates,

My Landy fired up within a second this morning, the very first start for the day and all the rest following  😎

This proves what many have claimed, that sudden hard starts are mostly caused by poor grounds. It's really nice hearing it flash start.

Have  a great day all.

Cheers.

 

[Peaklander]

Glad it’s sorted. Now it’s time to tell us where you are as I can’t see your location 😃☀️🏝🏖🌊

[Sandy Landy]

On 5/7/2022 at 11:55 AM, Peaklander said:

Glad it’s sorted. Now it’s time to tell us where you are as I can’t see your location 😃☀️🏝🏖🌊

🤣🤣 I am in an island where tons of Brits visit everyday, bought a lot of houses, villas and investment properties, B for Brits and B for the island 😃 .....Barbados. I have friends who visit here for 4 months a year from Frenton, they bring me all my Defender parts 🙂

I would purchase and ship my stuff to their house in the UK and then they bring it when they are visiting, sooooooo if you are visiting let me know, I need some small bits and bobs 😂

My Landy is starting perfectly well now, the reason below why it was not. 

The old lug did have a bolt and nut but had cracked and the chassis grounding strop had completely become unsoldered and completely loose. I re-clamped it and soldered it onto the cable again and changed the lug.

Cheers.

 

 

Edited May 9, 2022 by Sandy Landy