Help required Fuse 39 keeps blowing

[The Big Boulonnais]

Hi guys,

I am stuck on a camp site on holiday miles away from home and I found out that my indicators (also called turning lamps by some) are not working any more. After investigation I found out that Fuse 39 had blown. It protects the indicators but also the rear white reverse lamp. I replaced it by same model mini blade 10 A but it blew straight away. I tried without touching the indicators switch but by just turning the ignition to On and it blew Fuse 39 again.

I am out of ideas but I can tell there is a short somewhere but can't find where and I'm not supposed to drive like that as it's illegal.

Any one who has experienced the same problem or have a good idea of what could be the cause could you please help me?

Many thanks,

Chris

 

[eemain]

Haven`t experienced anything like this, but it is in the field of electricity that
I make a living.

Did you somehow get water in one of the sockets? Open up the taillights and see. While there remove the bulbs and try again with a new fuse. That is if you have more spare fuses. If it holds you may be able to track it down to the socket at least.

Can`t speak to how it is wired in the taillights as I haven`t seen wiring diagrams or even opened my taillights yet.

Hope this helps

 

[The Big Boulonnais]

Haven`t experienced anything like this, but it is in the field of electricity that
I make a living.

Did you somehow get water in one of the sockets? Open up the taillights and see. While there remove the bulbs and try again with a new fuse. That is if you have more spare fuses. If it holds you may be able to track it down to the socket at least.

Can`t speak to how it is wired in the taillights as I haven`t seen wiring diagrams or even opened my taillights yet.

Hope this helps

Hi,

Thanks for your reply but I forgot to mention earlier that all the indicators lights work when I press the Hazard switch so I don't think it is necessary to check all sockets.

I have no trailer and not even a trailer socket connected.

What happened is that I had a cool box connected to the rear cigarette lighter Friday on my way to camp site and I forgot to unplug it overnight so Saturday morning my main Battery was flat. My KJ has an auxiliary Battery properly wired via relay by a professional.
This battery is only there for my roof LEDs spot lights and just in case the main battery lets me down. So Saturday morning I had to turn a rotative switch to get the starter motor connected to battery 2 (auxiliary) instead of battery 1 (main). I started the car then turned the switch back to battery 1 so when driving the main battery gets recharged and the auxiliary takes the charge only when the main one is 95% full via a relay.

Like I said earlier this set up might seem dodgy but it was fitted by a professional 6 months ago and is commonly used by people with caravans or camper vans.

I welcome your suggestions.

Cheers,

Chris

 

[eemain]

The Jeep isn`t here right now for me to go turn the key and see what happens in the ON position.


What year? Maybe a schematic can be found online!

 

[eemain]

Looking at the manual that I have... Fuse 39 is tied into the Hazard switch combination Flasher by a DK. Blue/ White wire and is hot in run. Where it ties in its marked Ignition.



Don`t know if its different for you over there.

 

[The Big Boulonnais]

Looking at the manual that I have... Fuse 39 is tied into the Hazard switch combination Flasher by a DK. Blue/ White wire and is hot in run. Where it ties in its marked Ignition.



Don`t know if its different for you over there.

Hello eemain,

Thanks for taking the time to look into my troubles. My KJ is a 2.8 crd imported from USA and with a 2007 UK Reg plate but the VIN confirms that it was built in 2006.

I have access to Wifi here so yes I have also access to the service manual and the electric drawings. I found that Fuse 39 is also protecting the command of the Defroster relay but I cannot so far find that relay. I am going to get stuck in today as I've got some basic tools with me but unfortunately I left my Electrical Multimeter at home!

I will keep you posted if I find something. Thanks again for your help.

Chris

 

[Billwill]

As stated above...what year/model do you have? I have most year's circuit diagrams.

First thing I would do is pull the connector off your reverse switch...the reverse light will not light up but that is not major and see if the fuse still blows....this isolates some of the circuit.

Does the fuse blow when you activate the turn stalk one way or the other or does it blow when putting transmission into reverse?

I do not trust any battery system that switches from one battery to another unless it is very well designed....having the engine running on alternator only while momenterily disconnecting the battery and re-connecting the battery stands a good chance of blowing the PCM, TCM or BCM.
If the circuitry to switch the batteries is "make before brake" system ie. both batteries remain connected during the switch-over process then there is not a problem.


Your first issue is to stop the fuse blowing and then we can take things from there.


Surely it would be legal in the UK to drive home with your hazard lights flashing? irritating for sure but it does indicate that you have some form of problem!

Edit to add...I see you have updated your post to answer some of my questions. The de-fogger relay is located on the reverse-side of your internal fuse panel...it is not marked!

I will look through the 2006 CRD circuit diagrams and get back to you.

A word of warning here!

The USA models of the 2006 CRD have a known problem that where the wiring harness goes behind the bracket for the fuel filter...the bracket was re-located to make more space somewhere. There is a good chance that wires in this harness are fraying through to ground behind the fuel filter bracket.

You need to remove this bracket and have a good look at the wiring there!

 

[The Big Boulonnais]

As stated above...what year/model do you have? I have most year's circuit diagrams.

First thing I would do is pull the connector off your reverse switch...the reverse light will not light up but that is not major and see if the fuse still blows....this isolates some of the circuit.

Does the fuse blow when you activate the turn stalk one way or the other or does it blow when putting transmission into reverse?

I do not trust any battery system that switches from one battery to another unless it is very well designed....having the engine running on alternator only while momenterily disconnecting the battery and re-connecting the battery stands a good chance of blowing the PCM, TCM or BCM.
If the circuitry to switch the batteries is "make before brake" system ie. both batteries remain connected during the switch-over process then there is not a problem.


Your first issue is to stop the fuse blowing and then we can take things from there.


Surely it would be legal in the UK to drive home with your hazard lights flashing? irritating for sure but it does indicate that you have some form of problem!

Edit to add...I see you have updated your post to answer some of my questions. The de-fogger relay is located on the reverse-side of your internal fuse panel...it is not marked!

I will look through the 2006 CRD circuit diagrams and get back to you.

A word of warning here!

The USA models of the 2006 CRD have a known problem that where the wiring harness goes behind the bracket for the fuel filter...the bracket was re-located to make more space somewhere. There is a good chance that wires in this harness are fraying through to ground behind the fuel filter bracket.

You need to remove this bracket and have a good look at the wiring there!

Hi BillWill,

Thank you for your suggestions.

I don't even have to touch the stalk to blow the fuse. As soon as the key in the ignition goes to On Fuse 39 blows immediately this is without starting the engine.

I went out with the Jeep today and bought a multimeter and I had a look at the wires harnesses under the car but still have to give a proper look to the one behind the fuel filter.

We are moving camp site tomorrow morning about 3 hrs drive so I don't want to make things worse now but once I arrived I will investigate again.

Thanks for keeping in touch.

Chris

 

[yellocoyote]

Sounds like a faulty bulb socket. I had that happen to my front indicator lights and I went through fuses like crazy until I located the issue.

 

[mightybeet]

i had a weird issue where my signals didnt activate from the multifunction switch and reverse lights didnt work. but hazards worked. no one could figure it out. my mechanic found fuse 39 went but still had signal issues and i wasnt gonna pay something craycray for a diagnostic. i traced it to the wire harness going to my reverse switch near the transmission. the harness was not tied down to anything and drooped on to the front drive shaft. that eventually rubbed right through all but 2 wires. wire connectors and crimp tooled back together. not saying its the same but its a shot.

 

[Billwill]

i had a weird issue where my signals didnt activate from the multifunction switch and reverse lights didnt work. but hazards worked. no one could figure it out. my mechanic found fuse 39 went but still had signal issues and i wasnt gonna pay something craycray for a diagnostic. i traced it to the wire harness going to my reverse switch near the transmission. the harness was not tied down to anything and drooped on to the front drive shaft. that eventually rubbed right through all but 2 wires. wire connectors and crimp tooled back together. not saying its the same but its a shot.

Yep that is why I suggested the OP disconnect the plug from the reverse switch but I forgot to mention that while he was doing this he needs to check the wiring for fraying to ground somewhere!:icon_wink:

 

[The Big Boulonnais]

Hi Mightybeet,,

I checked the wire harness that goes to the transmission and I can't find anything wrong there. Well spotted though as that harness could eventually get detached by a branch or something when off roading.

Still have to remove my fuel filter to check behind it as advised by BillWill but I start to believe that the switch/stalk on the left of the steering wheel is faulty.

Chris

 

[The Big Boulonnais]

Yep that is why I suggested the OP disconnect the plug from the reverse switch but I forgot to mention that while he was doing this he needs to check the wiring for fraying to ground somewhere!:icon_wink:

Hi BillWill,

Sorry for delay but yesterday I spent all day moving site but this morning I went back to it. I checked behind the fuel filter but all looks good so I went back under the Jeep and unplugged two connectors coming from the same harness.
I started removing the wires from their plastic sheath to see if they have any signs of damage but once I got the wires up to the engine bay it becomes really difficult to follow them. Anyway now I've got a Multimeter I tested them and one of the connectors is clearly in short circuit. I believe that's the one that goes to the reverse switch. I don't know what the other one is.
I tried with a new 10 Amp fuse and the 2 connectors disconnected and again the fuse blew just by turning the ignition to On.

I am going to try to check the stalk/switch at the steering wheel as I can't keep taking all the wiring apart as I'm not in a garage but in the open on a camp site but Thank God the weather is good!

Cheers,

Chris

 

[Billwill]

Hi BillWill,

Sorry for delay but yesterday I spent all day moving site but this morning I went back to it. I checked behind the fuel filter but all looks good so I went back under the Jeep and unplugged two connectors coming from the same harness.
I started removing the wires from their plastic sheath to see if they have any signs of damage but once I got the wires up to the engine bay it becomes really difficult to follow them. Anyway now I've got a Multimeter I tested them and one of the connectors is clearly in short circuit. I believe that's the one that goes to the reverse switch. I don't know what the other one is.
I tried with a new 10 Amp fuse and the 2 connectors disconnected and again the fuse blew just by turning the ignition to On.

I am going to try to check the stalk/switch at the steering wheel as I can't keep taking all the wiring apart as I'm not in a garage but in the open on a camp site but Thank God the weather is good!

Cheers,

Chris

I cannot see how the stalk switch can blow fuse 39.....if you look at the circuit diagram all that the stalk switch for the turn signals does is switch ground via the central common contact to either the left or the right position.

So in other words, the wiring in this area goes to ground anyway.

What colour...note the spelling...wire do you measure is shorting to ground ?

 

[The Big Boulonnais]

I cannot see how the stalk switch can blow fuse 39.....if you look at the circuit diagram all that the stalk switch for the turn signals does is switch ground via the central common contact to either the left or the right position.

So in other words, the wiring in this area goes to ground anyway.

What colour...note the spelling...wire do you measure is shorting to ground ?

Hi Billwill,

I can't check the electrical schematics anymore as unfortunately we haven't got Wifi on this site and the only Cyber cafe in town was closed today.

So I went back under the Jeep to answer your question.

There is 2 lots of 2 wires going to connectors onto the Transmission. These 4 wires come from the same harness and separate into 2 smaller harnesses.
The one that goes to the furthest rear point of the Transmission has Brown/white wire and Blue wire. There is no short between the two wires when tested with Multimeter but there is a short between Ground and Blue.

The other connector goes to the side at about mid lenght of the Transmission which is what I believe to be the Reverse Switch but I am not 100% sure.
This connector has White wire and a Blue wire. Here we have short circuit between Blue and Ground, short between White and Ground and of course short between the Blue and the White wires.

Looking forward to know what you think of this.

Chris

 

[Billwill]

Hi Billwill,

I can't check the electrical schematics anymore as unfortunately we haven't got Wifi on this site and the only Cyber cafe in town was closed today.

So I went back under the Jeep to answer your question.

There is 2 lots of 2 wires going to connectors onto the Transmission. These 4 wires come from the same harness and separate into 2 smaller harnesses.
The one that goes to the furthest rear point of the Transmission has Brown/white wire and Blue wire. There is no short between the two wires when tested with Multimeter but there is a short between Ground and Blue.

The other connector goes to the side at about mid lenght of the Transmission which is what I believe to be the Reverse Switch but I am not 100% sure.
This connector has White wire and a Blue wire. Here we have short circuit between Blue and Ground, short between White and Ground and of course short between the Blue and the White wires.

Looking forward to know what you think of this.

Chris

The Dark Blue wire carries +12 volts to the Reverse Switch as well as to the Hazard Switch. The other side of the Reverse Switch is a White/Gray wire going to each rear Reverse lamp. This Dark Blue wire must not have a direct short to ground.

I would disconnect first connector C1 then connector C3 (8W-12-25) on the Junction Block to see which of the Dark blue wires is going to ground. The Junction Block is basically the internal fuse panel.

Then if needs be cut the faulty wire two inches away from the connector ie. Pin 38 C1 or Pin 32 C3. You can always re-solder the wires back together and insulate with heat shrink tubing.

I will have alook for the connector at your transmission that has the Brown/White wire.

Here are the diagrams:

 

[The Big Boulonnais]

The Dark Blue wire carries +12 volts to the Reverse Switch as well as to the Hazard Switch. The other side of the Reverse Switch is a White/Gray wire going to each rear Reverse lamp. This Dark Blue wire must not have a direct short to ground.

I would disconnect first connector C1 then connector C3 (8W-12-25) on the Junction Block to see which of the Dark blue wires is going to ground. The Junction Block is basically the internal fuse panel.

Then if needs be cut the faulty wire two inches away from the connector ie. Pin 38 C1 or Pin 32 C3. You can always re-solder the wires back together and insulate with heat shrink tubing.

I will have alook for the connector at your transmission that has the Brown/White wire.

Here are the diagrams:

Hi BillWill,

Thank you for your support and for providing the electric diagrams.

I went back to the Cyber Cafe today and printed the Diagrams as I couldn't see them clearly on my Iphone.

Back at the camp I had a go at the Junction Block as you advised me.

The thing is there is a harness with about something like 50 or more wires going to the top of the Junction Block where Fuse 39 is. I didn't dare to disconnect any wire as it's not as straightforward as it looks on the plan. I am also a bit worried to do worse because we are going to Wales tomorrow for 3 days of Off Roading with other guys and I don't really want to get stuck here on a camp site in Somerset. I know that sounds a bit sheepish but once back home next week I will dare to tackle the job in Depth.

Thanks for all your messages so far. They have been a great help and now I'm getting some idea of what I'll need to do when I return home on Monday.

If that's ok with you I will write to update you on my progress and welcome your help again.

Cheers,

Chris

 

[TwoBobsKJ]

Just a quick comment...

This thread is all that is great about JeepKJ Country. Billwill, you've offered great detailed advice to The Big Boulonnais just because you want to help out a fellow Jeeper. Cheers, I'm gonna toast you with a pint tonight :favorites13:

And Big B, I hope you get these electrical gremlins figured out if for no other reason than the satisfaction of getting it done with a Jeeping partner from the southern hemisphere. Enjoy your time in Wales - the homeland of my grandfather! :waytogo:

Bob

 

[Billwill]

Just a quick comment...

This thread is all that is great about JeepKJ Country. Billwill, you've offered great detailed advice to The Big Boulonnais just because you want to help out a fellow Jeeper. Cheers, I'm gonna toast you with a pint tonight :favorites13:

And Big B, I hope you get these electrical gremlins figured out if for no other reason than the satisfaction of getting it done with a Jeeping partner from the southern hemisphere. Enjoy your time in Wales - the homeland of my grandfather! :waytogo:

Bob

Thanks TwoBobsKJ.....my maternal grandfather also came from Wales...prospected for diamonds here in SA his whole life although his right arm was completely pulled off by a piece of machinery.

I am retired now but qualified in Electrical Engineering Light Current and spent 34 years in Support fixing Mainframe Computers and peripherals....ten years with IBM then with Hitachi....as well as working on Industrial Robots from Westinghouse, Bosch and GMFanuc so I know my way around electrical machinery.

I like spending my spare time helping others out with electrical problems on several Jeep forums as well as some BMW E30 forums I frequent....what goes around comes around....I have been assisted greatly in return on issues that I have had on these various vehicles.:icon_cool:

 

[The Big Boulonnais]

Thanks TwoBobsKJ.....my maternal grandfather also came from Wales...prospected for diamonds here in SA his whole life although his right arm was completely pulled off by a piece of machinery.

I am retired now but qualified in Electrical Engineering Light Current and spent 34 years in Support fixing Mainframe Computers and peripherals....ten years with IBM then with Hitachi....as well as working on Industrial Robots from Westinghouse, Bosch and GMFanuc so I know my way around electrical machinery.

I like spending my spare time helping others out with electrical problems on several Jeep forums as well as some BMW E30 forums I frequent....what goes around comes around....I have been assisted greatly in return on issues that I have had on these various vehicles.:icon_cool:

Hi BillWill,

I am really sorry for not writing for 4 days but all the time I was in Wales I never had 3G on my Iphone and there was no Wifi either. We couldn't even get a phone signal at the Campsite we were in Brecon Beacons National Park!

Apart from that it was really Beautiful !! What a Superb Scenery !! I had a great time off roading there with 5 other 4x4 and I am proud to say that despite that I was the only one with a Jeep I am not the one who ended up on its side. And apart from my trouble with my indicators I came back with almost no damage apart from a small hole in the rubber only on the side wall of my front tyre but I drove back home like that and we arrived in one piece yesterday evening.

I am going to see a friend of mine who has his own garage to try to get a computer connected to the jeep to see if there is another problem than the faulty wire (ie: faulty PCM or else) and I will keep you updated.

Cheers,

Chris