Wiring harness degradation photos

[Jelmer]

Per Gerry's request, I have taken some pictures my wiring harness. The idea is that this thread becomes a collection of damaged wiring harnesses, possibly also of other components that fail often. If you have pictures stuff you replaced, please add them here.

Hmm, a pity you can't put the attachments inline with comments, so I'll describe them

s_P7200790: ETA (right?) has been replaced.
s_P7200791: Dirty...
s_P7200792: Tape?!
s_P7200793: The harness!
s_P7200794: Close-up
s_P7200795: Wires? Check. Insulation? Not much.
s_P7200796: Those parts fell off when I pulled it out of the bag...
s_P7200797: No idea what it is, just know that it's incredibly brittle.
s_P7200798: Yeah, that's supposed to be flexible. Now it's only breakable.
s_P7200799: The alarm that was pulled. What a mess.

 

[Christian_K]

Here are mine from an E420 ^^

 

[gerryvz]

Here are my wiring harness photos ...

 

[Seangbadee]

I started coupling my (1995 E320) blower assembly back and noticed that a group of wires running with the positive cable with the tape unwrapping. I was unprepared for what I was about to see. Wires breaking up? This is a big risk here. I was able to get a few pictures including one with a tag attached to these wires. Can you help me identify these wires ? Is this the starter harness?

I’m looking on the forum for answers.

Thank you

 

[Duh_Vinci]

Learn something new every day, I thought wiring issues were limited to: Main harness, lower harness, ETA and MAF in some models of affected m119/m104 fitted cars, but I guess there is more!

 

[Seangbadee]

Learn something new every day, I thought wiring issues were limited to: Main harness, lower harness, ETA and MAF in some models of affected m119/m104 fitted cars, but I guess there is more!

Do you have any idea which wires these are?

 

[Seangbadee]

Do you have any idea which wires these are?

Took a closer look and found these numbers!
The part is NLA but someone mentioned on BW that Blue Ridge MB may rebuild the harness.

 

[Duh_Vinci]

Took a closer look and found these numbers!
The part is NLA but someone mentioned on BW that Blue Ridge MB may rebuild the harness.

Sorry, no idea to what this harness/wire this set would be... @jhodg5ck is a long standing and contributing member here, and IS the "face" behind the Blue Ridge MB. They do rebuild harnesses indeed, reach out to him...

Regards,
D

 

[Seangbadee]

Sorry, no idea to what this harness/wire set would be... @jhodg5ck is a long standing and contributing member here, and IS the "face" behind the Blue Ridge MB. They do rebuild harnesses indeed, reach out to him...

Regards,
D

Thanks

 

[gsxr]

There's an eBay seller with home-rebuilt W124/M104 starter harnesses, see link below. Note that is $200 for ONLY the three smaller wires, it does not include the main battery cable. (!!!) This is a sub-assembly of the complete harness 1245404230. The ad is a bit misleading IMO.

No affiliation, etc.

Mercedes W124 300E 2.8 E320 300CE 300TE 93-95 Lower Engine Harness Starter Oil | eBay

300E 2.8 300E 3.2 E320 and E300 diesel W124 models only! made from scratch with new plastic connectors.

www.ebay.com

Mercedes benz W124 lower engine wiring harness for starter/ oil pressure and oil level sender wiring harness loom. New made from scratch with European grade size wires made by Delphi. I have also listed some photos from the old biodegradable harness before and after. Again.. made from scratch with new plastic connectors.. Tested inspected on running car/ engine. Delphi made updated version Fits 1993 - 94 1995 and some 1996 models (E320 coupe cabriolet and station wagons) 300E 2.8 300E 3.2 E320 and E300 diesel W124 models only!! Part number: 124-540-42-30 This updated lower engine wiring harness is for starter positive/ starter engagement/ oil level sensor connector/ oil pressure connector. ***Tested and inspected! On running car/engine***

 

[Seangbadee]

There's an eBay seller with home-rebuilt W124/M104 starter harnesses, see link below. Note that is $200 for ONLY the three smaller wires, it does not include the main battery cable. (!!!) This is a sub-assembly of the complete harness 1245404230. The ad is a bit misleading IMO.

No affiliation, etc.

Mercedes W124 300E 2.8 E320 300CE 300TE 93-95 Lower Engine Harness Starter Oil | eBay

300E 2.8 300E 3.2 E320 and E300 diesel W124 models only! made from scratch with new plastic connectors.

www.ebay.com

Mercedes benz W124 lower engine wiring harness for starter/ oil pressure and oil level sender wiring harness loom. New made from scratch with European grade size wires made by Delphi. I have also listed some photos from the old biodegradable harness before and after. Again.. made from scratch with new plastic connectors.. Tested inspected on running car/ engine. Delphi made updated version Fits 1993 - 94 1995 and some 1996 models (E320 coupe cabriolet and station wagons) 300E 2.8 300E 3.2 E320 and E300 diesel W124 models only!! Part number: 124-540-42-30 This updated lower engine wiring harness is for starter positive/ starter engagement/ oil level sensor connector/ oil pressure connector. ***Tested and inspected! On running car/engine***

View attachment 135742

I’ll check that out too. I just noticed you mentioned Blue Ridge MB 1 year
ago

 

[JC220]

You could rebuild the harness yourself. It's not terribly difficult just replace one wire at a time with quality matching gauge automotive wire. If you are so inclined that is.

 

[Seangbadee]

You could rebuild the harness yourself. It's not terribly difficult just replace one wire at a time with quality matching gauge automotive wire. If you are so inclined that is.

I’ve been doing some reading and SXL wires is the best wire to use and not primary automotive wire

 

[Seangbadee]

You could rebuild the harness yourself. It's not terribly difficult just replace one wire at a time with quality matching gauge automotive wire. If you are so inclined that is.

I’m still reading around rebuilding the harness myself.

 

[JC220]

I’ve been doing some reading and SXL wires is the best wire to use and not primary automotive wire

Yes fair point was just stating that at a minimum make sure the wire selected is suitable for the purpose. Eg a hobby spec wire may not be suitable to exposure with an engine compartment. I solder all fittings, use quality glue lined heat shrink and Tesa tape. Looks good as factory.

Its cheap materials but the investment is in your time! I would only repair where I cannot get a non degradable replacement.

 

[Seangbadee]

Yes fair point was just stating that at a minimum make sure the wire selected is suitable for the purpose. Eg a hobby spec wire may not be suitable to exposure with an engine compartment. I solder all fittings, use quality glue lined heat shrink and Tesa tape. Looks good as factory.

Its cheap materials but the investment is in your time! I would only repair where I cannot get a non degradable replacement.

I intend to rebuild end to end. I'm trying to get the right guage wires before I start the project. Heaven knows what else I will find!

 

[JC220]

Remember also the original harnesses fail because in their wisdom MB used some sort of soya bean based eco friendly wire insulation as we know.

Therefore any wire insulation suitable for automotive use should be just fine. It is not an extreme environment requiring military grade components. It was a design flaw in the original materials.

 

[gerryvz]

This is a very very simple harness to rebuild -- much less complicated than the lower harnesses for the M119 and M117 engines. It's just basically a connection between the positive terminal of the battery to the starter.

I would highly recommend having @jhodg5ck and his crew rebuild the harness, or if you are adventurous, do it yourself. I have visited the Blue Ridge facility and they have a specific room in their shop that is dedicated to rebuilding harnesses. This is how much of the work that they do for their customers.

Cheers,
Gerry

 

[Seangbadee]

This is a very very simple harness to rebuild -- much less complicated than the lower harnesses for the M119 and M117 engines. It's just basically a connection between the positive terminal of the battery to the starter.

I would highly recommend having @jhodg5ck and his crew rebuild the harness, or if you are adventurous, do it yourself. I have visited the Blue Ridge facility and they have a specific room in their shop that is dedicated to rebuilding harnesses. This is how much of the work that they do for their customers.

Cheers,
Gerry

Thanks Gerry. I’m still trying to reach Jonathan. @gsxr sent me a schematic, and I tried but could not interpret it

 

[gsxr]

Just sent the secret decoder ring... enjoy!

 

[Seangbadee]

Just sent the secret decoder ring... enjoy!

Got it!

 

[Seangbadee]

Just sent the secret decoder ring... enjoy!

The white/violet is the thicker of the 3, and is 2.5mm which is a 14 gauge
The brown/black is 0.75mm which is 20 gauge
The brown/green is also 0.75mm.
Now for the great question?
Is it advisable to use 18 gauge instead of 20, and 12 gauge instead of 14?
Personally I don’t think it will hurt but I just need a few different ideas.
Thanks all.

 

[Type5314]

Wiring harness pics: 1992 500 E. Domiciled in Pennsylvania from new (March 1992) until December 2007. Mileage 47,100. Always garaged. Transferred with original owner to Las Vegas beginning 2008 until June 2021. Mileage 67,200. Again, garaged. Low mileage and good care don't matter. The original wiring harnesses self-destruct. I believe these harnesses are limited to early 90's cars with LH injection. So my 1992 300 TE with the 103.983 engine and CIS-E (KE) injection is not at risk for this particular issue.

Upper harness:









Lower harness:

 

[gsxr]

Now for the great question?
Is it advisable to use 18 gauge instead of 20, and 12 gauge instead of 14?
Personally I don’t think it will hurt but I just need a few different ideas.

Yes - I would go 1 size larger for both. In particular, 20 gauge is too delicate IMO. Even 18-ga is pretty thin. The only downside to large cable is if you have size or space constraints; OR where the lack of flexibility will cause problems due to routing or vibration concerns. This should not be an issue with only 1-size larger assuming the wire you use has normal-thickness insulation with a high temp rating.

 

[Seangbadee]

Yes - I would go 1 size larger for both. In particular, 20 gauge is too delicate IMO. Even 18-ga is pretty thin. The only downside to large cable is if you have size or space constraints; OR where the lack of flexibility will cause problems due to routing or vibration concerns. This should not be an issue with only 1-size larger assuming the wire you use has normal-thickness insulation with a high temp rating.

I have a choice between TXL, GXL and SXL. TXL has the thinnest insulation and SXL is the thickest one. GXL has a thickness in between those two. I’m still shopping around.

SXL Automotive Primary Wire | Allied Wire and Cable

Upgrade your vehicle's electrical systems with our SXL automotive primary wire, known for its enhanced insulation and high-temperature resistance. This wire is designed to withstand severe environmental conditions, ensuring safety and efficiency in demanding automotive applications.

www.awcwire.com

 

[gerryvz]

Wiring harness pics: 1992 500 E. Domiciled in Pennsylvania from new (March 1992) until December 2007. Mileage 47,100. Always garaged. Transferred with original owner to Las Vegas beginning 2008 until June 2021. Mileage 67,200. Again, garaged. Low mileage and good care don't matter. The original wiring harnesses self-destruct. I believe these harnesses are limited to early 90's cars with LH injection. So my 1992 300 TE with the 103.983 engine and CIS-E (KE) injection is not at risk for this particular issue.

M104.99x engines with HFM fuel injection, from US model year 1993-1995 also have this issue. This goes for all cars with the HFM injection -- W140, R129, W124, W202, and even W463 (G-wagen) models, such as the 1995 G320 that I own. Upper and lower engine wiring harnesses.

CIS-E-based engines (M103, M117, and non-HFM M104 engines) did not have this issue. LH-based V-12 engines also had this issue in the affected model years.

The issue does not seem to affect W210 models - particularly after about 1996 (HFM or later six-cylinder models).

 

[Type5314]

Thanks, Gerry, that’s the clearest answer I’ve ever seen on the subject

 

[gsxr]

And, all models with LH-SFI injection have the wiring issue for the engine harnesses. This would be limited to 1992-1995 USA model years on select 124, 129, and 140 chassis.

 

[Seangbadee]

Yes - I would go 1 size larger for both. In particular, 20 gauge is too delicate IMO. Even 18-ga is pretty thin. The only downside to large cable is if you have size or space constraints; OR where the lack of flexibility will cause problems due to routing or vibration concerns. This should not be an issue with only 1-size larger assuming the wire you use has normal-thickness insulation with a high temp rating.

I finally rebuilt my lower harness using 18ga and 12ga GXL automotive wiring. I wrapped them individually and made sure I paid attention to the exact point of bifurcation using the original harness as my template.
This is what the final harness looks like. I intend to wrap the bundles in thermal sleeves to further protect them.
My ETA (10/95 stamp) definitely has to go to Don for rebuilding. The protective tubing was split in the car revealing the biodegradable mess.