Taillamp fuse blows immediately

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johnburdine

New member
I have a 2004 Dodge Sprinter. I noticed I didn't have taillights. My Headlights, Rear brake lights and turn signals all work. I found that both taillamp bulbs (lowest ones in back) were bad. Checked the fuse box in the steering column and fuse #11 (10A) was blown. Fuse #1 is good. So I pulled the bad bulbs so there wasn't anything in those sockets at all and put a new fuse in spot #11. Started the van. When I would switch the headlights on while idling, the engine would work a little harder then the fuse would pop. Happened twice. I assume there is a short somewhere that is bogging down the alternator. Am I right??? How do I fix this or at least isolate the problem? Thanks!!
 
D

Dingo

New member
Evening , the most common fault in the rear lights i have encountered is the metal tracks on the bulb holder corrdoing & dropping across onto other tracks . If the one it touches is the earth bang goes your fuse , real easy to check , just unclip holder & pull off connector & look in bright light . Any broken tracks are easily noticed . have seen several vasn where the rear light clusters do not seal against the body & allow water to track around the lens and spoli the tracks . Speak to a body shop about foam sealing tape , both wurth & 3M make these tapes . Clean & stick them to the body aparture & refit lights .

hope this helps you
 
J

johnburdine

New member
Dingo said:
Evening , the most common fault in the rear lights i have encountered is the metal tracks on the bulb holder corrdoing & dropping across onto other tracks . If the one it touches is the earth bang goes your fuse , real easy to check , just unclip holder & pull off connector & look in bright light . Any broken tracks are easily noticed . have seen several vasn where the rear light clusters do not seal against the body & allow water to track around the lens and spoli the tracks . Speak to a body shop about foam sealing tape , both wurth & 3M make these tapes . Clean & stick them to the body aparture & refit lights .

hope this helps you
Click to expand...


I'll check it out thanks! Makes sense since my van had a tommy gate on it so there are some holes above the taillight assembly that could be allowing water in.
 
J

johnburdine

New member
Dingo said:
Evening , the most common fault in the rear lights i have encountered is the metal tracks on the bulb holder corrdoing & dropping across onto other tracks . If the one it touches is the earth bang goes your fuse , real easy to check , just unclip holder & pull off connector & look in bright light . Any broken tracks are easily noticed . have seen several vasn where the rear light clusters do not seal against the body & allow water to track around the lens and spoli the tracks . Speak to a body shop about foam sealing tape , both wurth & 3M make these tapes . Clean & stick them to the body aparture & refit lights .

hope this helps you
Click to expand...


So I checked into it and it doesn't look like the bulb holder is the problem. There was a bit of rust but I took a wire brush to it and nothing was across to the other tracks. I did try a new fuse and it's not just "popping" fuses, it's melting them. There's a bit of smoke, the fuse melts a bit, then it pops, when I pull it out the plastic comes off the metal teeth.
 
autostaretx

autostaretx

Erratic Member
slow melts indicate a current under about twice what the fuse is rated for.
So if it's a 10 amp fuse, it's probably seeing a 15 amp load or so.

The cable harness under the floor to the rear could be damaged (thrown rock crushing the wires together hard/sharp enough to damage the inter-wire insulation, or chafing against a sharp piece of the framework)

Pull all of the bulbs and see if the fuse melts.

The 2006 service manual available here is close enough to your 2004 to serve to trace down what else might be on that circuit...
You don't have a trailer hook-up, do you? Their connectors and wiring are renowned for adding issues...

--dick
 
thinice

thinice

2005 tall 140WB 160K
My taillight circuit board was slightly bent causing aching that triggered several dash warning lights when I turned on headlights. German Engineering? If your have not already tried? Unplug the taillight assemblies (easy to do, snap out from inside the van) and see if you still blow fuses. Might help narrow it down. Right and left are interchangeable which might help narrow it down further.
 
J

johnburdine

New member
Thanks for the tips...I'll look into them. I don't have a trailer harness but I did have that tommy gate so there was all sorts of wiring I just taped off since I'm not using them. I'll make sure they are not faulting. I also wonder if the problem is the fuse holder itself having a bad connection. Unfortunately my bolt holding the fuse block to the steering column is spinning in place. Also I read on here that I need to unhook a battery cable before messing with the fuse block...does anyone know which cable and from where???
 
autostaretx

autostaretx

Erratic Member
"Unhooking the battery" means removing either the positive or negative clamp from the battery post itself.
(the usual recommendation is to start with the negative post, since having your wrench slip and touch the metal bodywork won't cause spectacular problems (such as welding it in place)).

Then wait a few minutes, since you're letting the capacitors in the explosive air bags and seatbelt squibs drain their charges.

There are postings by Vic (aquaputana) on dealing with the spinning nut on the fuse block...
--dick
 
J

johnburdine

New member
So I pulled all the bulbs in back and it still blew the fuse. Does that eliminate the possibility of the cable harness underneath causing the problem?? Also, I think the melting is due to crappy generic fuses. I tried I higher quality one and it popped instantly. The fit felt much tighter on the quality one too.
 
autostaretx

autostaretx

Erratic Member
No, removing the bulbs does NOT eliminate the cable... it increases the likelihood.
Next up would be to unplug the connector near the tail light assembly.. that eliminates that puppy.
Chasing it down with an ohmmeter might help but you're facing a load that's less than one ohm ... at least it will appear as a near short-circuit.

In other cases (wiring running under the engine area) people have been able to find the damaged cable by feel... it's palpably different (stiffer and "crustier") where the wires are melting together....

Annnd... if you'd checked the schematic, you'd see that the wire that feeds the left tail light also feeds the left front headlight assembly.
(via splice 356 on page 8w-10-26) ((and there may be a lamp relay involved... are you Canadian with daytime running lights?))

So it could be your left front parking light or side lamp that's doing it (or the cable thereto)

Welcome to vague wiring issues...
--dick
 
J

johnburdine

New member
autostaretx said:
No, removing the bulbs does NOT eliminate the cable... it increases the likelihood.
Next up would be to unplug the connector near the tail light assembly.. that eliminates that puppy.
Chasing it down with an ohmmeter might help but you're facing a load that's less than one ohm ... at least it will appear as a near short-circuit.

In other cases (wiring running under the engine area) people have been able to find the damaged cable by feel... it's palpably different (stiffer and "crustier") where the wires are melting together....

Annnd... if you'd checked the schematic, you'd see that the wire that feeds the left tail light also feeds the left front headlight assembly.
(via splice 356 on page 8w-10-26) ((and there may be a lamp relay involved... are you Canadian with daytime running lights?))

So it could be your left front parking light or side lamp that's doing it (or the cable thereto)

Welcome to vague wiring issues...
--dick
Click to expand...
So the connector to the tail light assembly looks hard wired. Are you saying its a "quick connect" or do I need to trace the wiring back to find the disconnect point?

Also, I checked my left front parking light (didn't know I had one) and it is currently out, so I'm going to check to see if its the bulb that's bad. Why would my left front headlight work without a fuse in slot #11???
 
thinice

thinice

2005 tall 140WB 160K
Yes the taillight assembly is a quick disconnect at the assembly. Insert a small screwdriver to release (can't remember exactly were but it should be pretty obvious when your looking at it) and pull off plug.
 
autostaretx

autostaretx

Erratic Member
It's only the two (on each side) front parking light bulbs that are on the "taillamp" circuit... each headlamp has its own fuse
(my Sprinter has a tiny bulb in the headlamp area... if the headlamp is not on, that small bulb dimly illuminates its cup)
There is also the small (amber?) bulb that's visible from the side (but still in the headlamp assembly).

The wire that powers the parking lights on the left side is gray with a black stripe, running to pin 10 on the headlamp connector.
Some folks have found water and grunge contamination of that connector.

--dick
 
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J

johnburdine

New member
autostaretx said:
It's only the two (on each side) front parking light bulbs that are on the "taillamp" circuit... each headlamp has its own fuse
(my Sprinter has a tiny bulb in the headlamp area... if the headlamp is not on, that small bulb dimly illuminates its cup)
There is also the small (amber?) bulb that's visible from the side (but still in the headlamp assembly).

The wire that powers the parking lights on the left side is gray with a black stripe, running to pin 10 on the headlamp connector.
Some folks have found water and grunge contamination of that connector.

--dick
Click to expand...
Thanks, I'll look into that next. I did get the rear bulb housings unplugged and that didn't help anything. I also got the steering column fuse box down, but it looks like I will have to take the box apart to see the back side of where that particular fuse holder is, to make sure the wires are good there. I think I will trace that front wire first.
 
V

vanhousecustoms1

Van Builder DIY Mechanic Owned 15+ Sprinters 02-18
Thank you all for your help.

We're having a similar issue with our 06 Sprinter Camper. Left tail lights won't work - Fuse #11 blows immediately upon turning on headlights. We took apart the front headlight and all looks normal (Swapped bulb to right side and works like a charm). (Yes, Vic :smilewink:) We checked the fuses - all look good other than #11. It's not the tail light assembly (we've swapped them and they're both fine). We've replaced all the rear bulbs...

We do have a DIY trailer wiring harness installed (before we read about all the issues they cause) - maybe this is the problem? I inspected the splices and they're all secure and undamaged. Maybe not the problem because we're getting a good ground, brake light, turn signal, etc. at the tail light assembly? Still, should I remove the splices and tape up the wires?

Our latest possibility -- we screwed something up when we spray-foamed our camper walls. Perhaps we sprayed too much around the harness and the heat from the reaction melted the wiring (it's a solid block of foam from where the wires meet the assembly to where they poke out underneath the van... impossible to inspect...). This foam is usually not an issue around electrical, but maybe vehicle wiring is more sensitive or we applied it incorrectly? Can we order new wiring and replace this?

Trying to catch up on these forum posts to track down our own "vague wiring issue" with my limited understanding of electrical wiring... any help is much appreciated. :idunno:

If all else fails, we're thinking of rigging a wire from the right side tail light over to the left so that we have a working tail light... Bad idea? Brilliant idea? Who knows.

-Amanda, Miracle RVs

P.S. I think we've read every post on this tail light problem to no avail. Has anyone ever fixed this problem?
 
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