Tail light Repairs or Replacement

Aqua Puttana

Poly - Thread Finder
Tail light, taillight, brake light, rear light circuit, rear lamp, running light

Have more information? Feel free to add to this Write-up.
Have Questions? Please take questions to a new thread or tag on to another appropriate thread.

A quick search didn't reveal a Write-up thread specific to T1N Tail Lights. This is a compilation of some information. To see pictures/attachments related to the posts/threads just click on the blue arrow icon within any quote box. That will take you to the original post/thread.

This thread does have some repair info.
Rear Lamp Socket Assemblies

and here

Thanks to Billintomahawk :thumbup: I have a Chinese copy of the circuit board lamp holder assembly. It looks very similar to the OEM units on my 2004 and 2006. One difference is that there is no jumper to include the lower position as a running light. I have ordered a Dorman lamp unit to compare the two aftermarket replacement parts.

For now the compilation.

From Cheap Tricks.

ABS ESP Traction Lights On Brake Light Fuse (#5?) Blown Shift Locked

20151130, 20160928. 20190330 edit: As of today... 8+ years now, what some may consider a temporary repair with inserting the insulation material in the light assembly is still going strong. I'm thinking that the repair is quite permanent for me.

Yesterday my ABS, ESP and Traction (tire slipping symbol) lights came on. The van seemed fine except for the array of annoying lights on the dash. One caution I would give is that if those lights do come on you need to verify whether your brake lights are still working. Mine weren't and I didn't know ( or remember?) I needed to check the brake light operation. Therefore I didn't check the fuse immediately as I should have. (Fuse #5 under the steering column in my 2004 by the way.) Your cruise control will also not function. This is a Cheap Trick because I don't believe it is necessary to replace the tail light assembly to cure this particular shorting problem.

20100715 edit: I forgot to add that if the lights above come on the shifter will lock in Park. You will need to carefully use a small screwdriver or pencil pushed down through the little cover door below the "D" on the shifter to manually release the shift lever for Reverse-Neutral-Drive. Once the shifter is returned to Park it will need to be released manually again.

Your ignition key will work perfectly to release the shift lock. It is just long enough.

My method.
Use the ignition key to release the shift lever. Shift to neutral. Start the van and drive.

Revelations cease here.

I've read about people having trouble with the tail light traces. The traces are a galvanized metal array of conductors used in the rear light assembly to distribute power to all the tail lamps. They look too well designed to go bad. Well, the traces themselves don't go bad, but the other connections nearby may. There are two points on my 2004 NAFTA TIN dual filament tail/stop lamps which are close to the negative trace. In my case it was the right rear connector to the stop lamp pin which moved in and shorted the brake circuit to the negative (ground) trace. The metal end of the "stop" trace is pushed into that connection. The connection may have gotten hot and loosened the plastic holders? My inserted insulation in the form of nylon cable tie material trimmed to fit pushes that connection tight again. (At least that's the theory. I'll need to watch that it doesn't loosen and fail again.) In a pinch some slivers of whittled wood would also work fine as spacers/insulators.

This is where to look for the problems.

View attachment 24888

Both my photography and edit skills are marginal at best. The text above reads "Insulation Inserted In Two Places".

This is a picture of the entire parking light assembly traces.

View attachment 24887

I used paint sticks to color code the traces for another earlier troubleshooting session. It made it easier for me to follow what was going to where. I inserted insulation to all of my stop lamp potential problem areas (both sides = 4 total) to help avoid any future problems.

The colors I used on the traces were what I had that weren't dried up. The color scheme isn't logical. Yellow = tail lights. Red = stop light. Green = amber lens turn signal.

You may have noticed that I used some dabs of Goop glue to secure the plastic tie pieces in place even though they were tightly inserted. (You would notice that for sure if the picture was better.:doh:)

Too many fuses later after I finally successfully traced (pun intended) and repaired the problem, I figured I'd need my DAD to reset the codes for all the warning lights to go out. Fortunately I was also working on my steering column fuse block so I discovered that all you need to do is remove the added fuse block attached to the positive post for a minute or so. (Or disconnect the battery negative.) When it is reconnected the ABS, ESP, and Traction lights should all act normally, of course your radio and other toys may then need reprogramming too. The trouble codes remain in memory though.

Have fun. vic

A different failure mode on the 2004.

When my 2004 brake lights both failed I suspect that it didn't happen simultaneously. They both had similar corrosion on the spring/force fit interface between the steel trace and the socket brake filament/lamp connection (within the tail lamp assembly, not the external connector). One area probably corroded first going unnoticed and was followed some time later by the other failing.

My repair was to slip a hairpin of thin stiff wire - I used nickel wire approx. 20 AWG - into the compromised connection. That has been a permanent repair. I recommend that all T1N owners periodically spritz the tail lamp electrical parts with WD40. That should hold corrosion at bay. It is all covered in the link that I posted above.

Rear Lamp Socket Assemblies

View attachment 110348


20101006 edit:

There is more information related to troubleshooting the brake light system in this post starting about post #6. Thanks goes to all contributors.

Electrical issues - brake lights, cruise, ASR

Edit: Added misc info.

Another shift lock possibility with no ABS, Traction or other dash lights though.

I have had to replace 2 brake light switches on my 2005 for this same problem.

A different but similar problem: does the display tell you the transmission is in park?
If not, I just had and intermittent problem with mine doing the same thing and it turned out to be the transmission relay.
Dr. A gave me some starting places to do some testing of circuits and I stumbled upon the relay by accident.
It is the blue relay under the drivers seat at the front of the pedestal. When the trans wouldn't go into gear, I flicked
the relay with my finger and away she went. I do have to mention though that the display wasn't telling me which gear the
transmission was in when my problems occurred. After messing with the relay the display would work. Replaced the 15.00 relay
and now all is OK.
Some general info on wire colors for the rear lights.

Wiring I found:
Tail/Park: L = Gray/Blk, R = Gray/Red
Stop: L = Blk/Red, R = Blk/Red
Backup: L = Wht/Red, R = Wht/Red
Turn: L = Blk/Wht, R = Blk/Grn


View attachment 82001
ABS ESP Traction Lights On Brake Light Fuse (#5?) Blown Shift Locked

Tail lights on, turn signal on all the time

Here's a post related to trailer light modules and rear tail/brake lights.



Edit: My "Cheap Trick" recommendation is to check the drain holes that were found plugged before they ruin your modules and cause problems.

Thanks for the input in your previous post Farm Bus

This thread contains some good general information.

How to remove plug from rear light assembly

I still recommend giving the assemblies a spritz of WD40 when installed, or as preventative maintenance for older assemblies. Spritz the connector with WD40 or dab/coat with Vaseline before installing.

Have more information? Feel free to add to this Write-up.
Have Questions? Please take questions to a new thread or tag on to another appropriate thread.

:cheers: vic
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Aqua Puttana

Poly - Thread Finder
Be aware that some tail light aka rear light aftermarket units may not have an integrated jumper to power the bottom running light on OEM NAS aka NAFTA Sprinter tail lights.

Thanks goes to Patty&Ed and BillinTomahawk for some of the pictures. :thumbup:

Note that the Yellow colored traces are the Running Light Feeds on NAS aka NAFTA Sprinters.





Be aware.
I don't believe that both of the bottom tail running lights not being lit would be noticed for an annual safety inspection. If you run an OEM unit with an aftermarket unit which doesn't include the bottom running light power (jumper), the low position running light not being lit could result in being pulled over for a traffic safety inspection/infraction.

:cheers: vic


There is a relatively simple fix. Just install a small sheet metal screw to act as a jumper.


Expanded pictures from the Dorman website show that the Dorman 923-031 unit does have the lower lamp jumper to the running light circuit. I recall now that some Euro Sprinters have a rear fog lamp. The low lamp position is likely wired separately for that option.
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Aqua Puttana

Poly - Thread Finder
The Dorman vs eBay unit as promised.


Dorman 923-031

I haven't installed either unit yet. All of the lights on my T1N's are working. If it ain't broke...

Reports are that both units clip right in. By my eye they are both very similar in quality. The Dorman unit gets some extra credit for using copper, but either should work fine. Spritz all of the contact areas with WD40, coat with Vaseline, or electric contact lube before installing to help to avoid corrosion.

It's interesting to note that the OEM, eBay, and Dorman units all have little jump pieces which were cut after assembling and fastening to the plastic frame. (Refer to the various pics in the entire thread.)

The jump pieces keep the trace assembly in correct position until the plastic buttons are melted. On both units some of the cut jumpers seemed too close together for my taste. I recommend careful inspection of the multitude of cut jumpers before installing. I used a pair of small screwdrivers to wedge the ends apart a bit more. In some cases they were so close that I used a tiny pair of wire cutters to clip part of the jumper away.

I believe that the jumper ends being close together may explain some of the key out engine running until brake pedal is released incidents that get traced to the rear light units. Some cut jumpers are close enough that a bit of corrosion could bridge the gap. Refer to Post #2 picture #3 OEM unit above. Look at the top right of the pic.

I hear ya. A couple of years back i bought pattern part bulb holders (knowingly to save money) for the back lights and had no end of electrical problems (think DJ's disco lights whenever you switched them on) switched out to OEM parts and everything was fine, was definitely a case of buy cheap buy twice.
With little data, but lots of opinion I will comment that problems with aftermarket rear tail light units might very well trace to the clipped/bent jumpers. Some of the clipped pieces were close enough to each other that free water might be able to bridge the power when a bit of corrosion is added to the mix. Wet oxides will conduct electricity well. Aftermarket copying of the tail light assemblies is pretty basic stuff. The copies should work. Due diligence with adding gap to the many clipped jumpers will improve performance. :2cents:

On the OEM and Dorman units the one trace jumper is left in place for the NAS aka NAFTA lower position running light feed. I added the sheet metal screw to the eBay unit to restore the cut jumper.

:cheers: vic
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Well-known member
Looking at the layout, I can see that the bottom light could be wired to be a brake light. Is there a reason that you wouldn't want more brake lights?

Aqua Puttana

Poly - Thread Finder
Looking at the layout, I can see that the bottom light could be wired to be a brake light. Is there a reason that you wouldn't want more brake lights?
More/brighter brake lights isn't a bad thing from my vantage point. The high aka 3rd brake light was added to increase visibility. That said, having extra running lights has advantages also. Newer design vehicles have much brighter rear running lights than do our Sprinters. If you decide to add a brake light position, I would recommend installing a 21 watt lamp in the low position.

The ubiquitous 12 volt 1157 21/5 watt Brake/Running incandescent lamp must provide enough light (lumens) by itself to meet safety standards. That lamp is used alone on many vehicle brake/running lights (vans, trailers, trucks, etc.) The Sprinter OEM top position with 21/5 watts of incandescent light through a red lense alone should be good enough. Any added light is an enhancement for either brake or running light.

My guess as to why the bottom lense is used for a NAS aka NAFTA running lamp. The low position was there for mixed use. In Euro models it can be used for a rear fog light. It is an easy operation to leave the one trace jumper in place to make the bottom position an additional 5 watt running light. It would take a bit more effort/design to include it as an additional brake light.

:cheers: vic
Hey Guys...Any tips for preventing my brake lights from looking like an aquarium...???

During long rain storms my driver side taillight fills with water.

Hadn't driven the van in a few weeks. After starting her up and doing a quick walk around noticed water in the drivers side tail light. Upon closer inspection I observed mosquito larvae swimming in it.

Thinking of order up some Sea Monkey's...May as well have some mascots on board...LOL.



Erratic Member
Hey Guys...Any tips for preventing my brake lights from looking like an aquarium...???
Drill a drain hole at the bottom?

--dick (who used to have to do that to the rear floor of his VW squarebacks)(yes, plural)


'02 2.7 T!N Freightliner
Just did up my Chinese circuit board using the AP mod.
Got continuity between the top and bottom bulbs now.

Like Vic says , check the jumpers. I shoved a knife blade in between mine to increase the distance.

Looking ready for action now.


Aqua Puttana

Poly - Thread Finder
Brake/Run Lamp Contact Fix
Works for OEM and Dorman rear lamp units with wider contact pieces. May not work with some other aftermarket brand units because the one contact piece is much narrower.

I have had two different failure modes on the Brake/Run dual filament lamp holders.

It appeared that the problem with the 2004 was simple corrosion of the lamp contact to metal trace connection. The 2006 failure appeared to be that the spring contact assembly had shifted which caused the lamp contact pieces to move away from good contact to the solder button on the lamp. The 2004 may actually have been a combination of both of the conditions.

Regardless of the specific failure mode, a small U shaped ss solid wire inserted into the trace spring contact cured the problems.

The U shaped ss wire works for the brake/run lamp position. I don't believe that it will work on the other lamp positions. Those lamps use a different design to connect to the traces.

A picture should be worth a thousand words.



Added picture:

Apply Vaseline or contact grease to all of the connection points after the repairs, or at the least spritz them with WD40 or similar.

:cheers: vic
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New member
Thanks Aqua! Did you drop the small U shaped piece into that gap at the spring contact? Hard to see the u shaped metal in Pic #2. I will try it today.


Aqua Puttana

Poly - Thread Finder
Thanks Aqua! Did you drop the small U shaped piece into that gap at the spring contact?...
The U pieces were forced in using needle-nose pliers. I formed the U shape and when I cut it loose from the spooled wire I intentionally left one leg slightly longer. That made forcing the U piece in just a bit easier.


:cheers: vic
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Aqua Puttana

Poly - Thread Finder
Attempting to be proactive, today I removed the driver side tail light assembly. My plan was to install the U clips, grease things up, and avoid future problems. Turns out someone else had been there before me. The one pressure contact has what appears to be a 3/16" male slide-on connector forced into it. (A piece was clipped off.) The part looks good to me so I left it.

I installed a U clip in the other untouched pressure contact, greased things with Vaseline, and called it good.

If you have a 3/16" male slide connector or other appropriate sized brass flat stock, there is no reason to form custom U clips like I did.

As an aside. While checking other things I did notice a P2404 Stop Switch Implausible DTC. That may be related to the tail lamp assembly failures, but I don't know how it would be.

:cheers: vic


Active member
Would recommend using ACF-50 as a corrosion inhibitor for electrical devices. The film holds up a bit longer than WD-40. Or even a thin coat of LPS-3 rust inhibitor, it dries waxy and will stay in place for a long time.
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