Tail Fuse (15A) Blowing

Technical questions and answers about the Mazda Bongo

Moderators: Doone, westonwarrior

Post Reply
HairyBear
Apprentice Bongonaut
Posts: 3
Joined: Sun May 16, 2021 4:35 pm

Tail Fuse (15A) Blowing

Post by HairyBear » Sun May 16, 2021 4:54 pm

Hello all.

First post and as it goes, i'm asking for advice on a fault I cant seem to isolate!

Recently bought a June 1999 built 2.5 V6 in good overall condition.....

Having driven it without fault for a week, I noticed the Dashboard Lights (illumination) were not working, then to my annoyance whilst on the M5 at dusk the friendly drivers of the M5 advised me my tail lights were not working (sidelights). I have no idea if these lights have worked in my ownership (two weeks) however MoT was a few months ago so assume its a recent fault.

I checked the Tail fuse in the engine bay, which was blown....

Long story short, over the last few days I've isolated all the lighting (front, side and tail)... fuse continues to blow.

I also isolated the radio as there was an aftermarket radio fitted and ive read that may cause fuse to blow... fuse continues to blow.

I've looked on this website for wiring diagrams however, i'll admit to being overwhelmed with the hundreds of comments regarding the availability of a simple siring schedule.

To this end, i'm looking for any kind advice on this issue and, probably most importantly, a wiring scheduled to aid fault diagnosis.

Thanks in advance for any forthcoming help and advice....
User avatar
g8dhe
Supreme Being
Posts: 10180
Joined: Sun Apr 13, 2008 10:06 pm
Location: Worthing, West Sussex.
Contact:

Re: Tail Fuse (15A) Blowing

Post by g8dhe » Sun May 16, 2021 6:42 pm

You have just about the most difficult circuit to track down the loom runs all the way around the van, from the front side lights to the rear side lights.
Chances are it will most likely be at one of the lamp connectors, so take out each lamp check the lamp itself and then the exposed wiring to the lamp holder, if not the side lights then your down to checking each of the little display location lights dotted around the van (little green lamps) these are the next most likely places the final place will be if there has been any work carried out, welding, cleaning, moving conversion etc.
Geoff
2001 Aero V6, AFT, full side conversion.
Image Spherical Visions
HairyBear
Apprentice Bongonaut
Posts: 3
Joined: Sun May 16, 2021 4:35 pm

Re: Tail Fuse (15A) Blowing

Post by HairyBear » Mon May 17, 2021 6:45 pm

Thanks for you help.

Any idea where I can get a wiring diagram from?

I had another look today, played with the tailgate and the lights worked. But everything back together... spent last few hrs blowing fuses again.
User avatar
g8dhe
Supreme Being
Posts: 10180
Joined: Sun Apr 13, 2008 10:06 pm
Location: Worthing, West Sussex.
Contact:

Re: Tail Fuse (15A) Blowing

Post by g8dhe » Mon May 17, 2021 9:49 pm

The diagrams are not that useful in this sort of work, the only way of finding the short is visual inspection! If you've played with the tailgate and it cleared check carefully the loom within convoluted rubber tube that joins the tailgate to the chassis top right of tailgate, a common place for breaks due to the stresses.
Geoff
2001 Aero V6, AFT, full side conversion.
Image Spherical Visions
HairyBear
Apprentice Bongonaut
Posts: 3
Joined: Sun May 16, 2021 4:35 pm

Re: Tail Fuse (15A) Blowing

Post by HairyBear » Wed May 26, 2021 2:03 pm

So, been chasing this fault now for another week.

I disconnected two connectors under and to the left of the glovebox, which I saw had the side light cable (Green/red). I did this to try and isolate the looms to the tail.

No fault, put connectors together... no fault. Thought I’d fixed it. Now, fuse blowing again. Fuse now blowing with those two connectors disconnected.

Does anyone know if there are any more connectors which head to the rear of the bus?

If I put a continuity checker from the Green Red cable to Ground... what should I get? I’m obviously thinking I should get no continuity when lights off (or fuse out).... but can anyone supply any more info?

Where does the lead from the fuse box under the bonnet go to get distributed?
User avatar
g8dhe
Supreme Being
Posts: 10180
Joined: Sun Apr 13, 2008 10:06 pm
Location: Worthing, West Sussex.
Contact:

Re: Tail Fuse (15A) Blowing

Post by g8dhe » Wed May 26, 2021 3:38 pm

If you use a continuity tester then you will see every bulb in the system giving you continuity to earth :-( trying to disconnect every bulb is horrendous as all the little green location lights, background lights for the display etc are all on that same circuit ....
Start with the rear lights and visually inspect the connections and wiring, then check the front sidelights and the wiring to them, these are the most exposed and most common ones to suffer a problem and where the loom can get damaged very easily during maintenance etc.
Geoff
2001 Aero V6, AFT, full side conversion.
Image Spherical Visions
MaxHH
Apprentice Bongonaut
Posts: 9
Joined: Thu Jul 29, 2021 9:29 pm

Re: Tail Fuse (15A) Blowing

Post by MaxHH » Thu Jul 29, 2021 9:40 pm

Evening guys,

Any progress on your issue HairyBear?
Got same issue on my 2005 Aero, changed the dashboard lights for can bus leds, worked for a couple of weeks and now no more back lights on dash board and tail lights gone too.

Are the tail lights ment to be on the boot door or on the side clusters?

Something weird I noticed is that when I checked continuity on the bulb holder in the middle of the cups holder in the middle bay I get continuity even when no bulb is in, I would thought it is not normal.

I'll explore a bit more and let you know if I find anything.

Cheers
Maxime
User avatar
g8dhe
Supreme Being
Posts: 10180
Joined: Sun Apr 13, 2008 10:06 pm
Location: Worthing, West Sussex.
Contact:

Re: Tail Fuse (15A) Blowing

Post by g8dhe » Thu Jul 29, 2021 9:44 pm

As there are several lamps all in parallel you will always see continuity thru one or more lamps!
The tail lights are in the side clusters - at least in the older vehicles.
Fitting any type of LED is not a good move the reflectors and circuitry are not designed to use them.
Geoff
2001 Aero V6, AFT, full side conversion.
Image Spherical Visions
MaxHH
Apprentice Bongonaut
Posts: 9
Joined: Thu Jul 29, 2021 9:29 pm

Re: Tail Fuse (15A) Blowing

Post by MaxHH » Thu Jul 29, 2021 10:12 pm

Make sense now about continuity, thx for explaining.

Good to know about the LED, shame it made such a difference compare to the dull old bulb, will revert to old bulb. Do you think it could have melt a cable or blown a relay?
User avatar
g8dhe
Supreme Being
Posts: 10180
Joined: Sun Apr 13, 2008 10:06 pm
Location: Worthing, West Sussex.
Contact:

Re: Tail Fuse (15A) Blowing

Post by g8dhe » Fri Jul 30, 2021 9:23 am

Difficult to be certain, my first guess will be the LED's are faulty, unless they are from a well known manufacturer and CE marked then my guess would be duff ones of poor quality, much the same as solar panels, the cells / diodes are tested by manufacturers and only the real grade A ones used, the rest are sold off cheap and appear again with a lot of sales/marketing words around them :-(
Geoff
2001 Aero V6, AFT, full side conversion.
Image Spherical Visions
MaxHH
Apprentice Bongonaut
Posts: 9
Joined: Thu Jul 29, 2021 9:29 pm

Re: Tail Fuse (15A) Blowing

Post by MaxHH » Fri Jul 30, 2021 8:21 pm

Hum I see, well I am going to disconnect the dashboard in a minute and replace de fuse that blew and see if it comes from there.
MaxHH
Apprentice Bongonaut
Posts: 9
Joined: Thu Jul 29, 2021 9:29 pm

Re: Tail Fuse (15A) Blowing

Post by MaxHH » Fri Jul 30, 2021 9:51 pm

Disconnected the dashboard and fuse blew again so not coming from here.
I guess like HairyBeard did I should be disconnecting looms on both side (near glove box and close to gas pedal) that go to clusters, it would help me to figure out if short comes from the front or the back of the vehicule right?

Never came across those connectors, any tips on disconnecting them? Can see a grey T shape piece in the middle that looks like it wants to be pushed.
Attachments
IMG_20210730_213414(1).jpg
IMG_20210730_211830.jpg
User avatar
Northern Bongolow
Supreme Being
Posts: 7713
Joined: Mon Mar 15, 2010 11:33 pm
Location: AKA Vanessa

Re: Tail Fuse (15A) Blowing

Post by Northern Bongolow » Fri Jul 30, 2021 11:11 pm

Like Geoff says earlier, check the wiring that goes from body to tailgate top right of tailgate, number plate lights construction are not one of Mazdas better design efforts.
The wires are inside a rubber boot and usually are broken.
Post Reply

Return to “Techie Stuff”