I swear this wiring harness almost ended my career as a mechanic. Back sometime in 1999-2000 I was 18 and working as a mechanic. A customer brought in a 1995 W202 C280 for a small service including spark plugs. I changed the plugs using brand new factory parts and took the car out for a test drive. The car was running on like 3 cylinders, it had a ton of trouble codes, I was terrified. Beyond being scared I was so confused, I could not understand what I did wrong. It turned out when I unplugged the coil packs the wiring up inside the harness cover had the insulation fall off and everything started shorting out. When just looking at it appeared perfect. We told the customer their car needed a new wiring harness and they were unable to drive out in their car They did not believe us and were sure we were conning them. They towed the car to the Mercedes dealership and they told them the same thing. The customer then argued with Mercedes and wanted them to replace the wiring for free. Mercedes said, since the customer was not the original owner, the car was outside of its warranty, and the customer bought the Mercedes from a non-franchise Mercedes dealership they had no liability to fix the car. They went on to say that whoever detailed the car before they bought it used an improper cleaner that damaged the wiring harness and it was not a fault from Mercedes. Obviously a lie. This one car almost made me walk away from a lifetime career, I am still a mechanic to this day 20+ years later. Final details. The car was a 1995 C280 with 90-100k miles, the car was black and parked outside in California so it is possible that the engine harness got really hot. This took place at the end of 1999 or early 2000. The customer took it to a third shop and they replaced the harness for if I remember $1,100-$1,200 using a new OEM Mercedes harness. I believe my boss didn't charge the customer for the service of plugs, oil, filter, and tire rotation. Even though he really should have charged them, he was not willing to pay anything towards the wiring repair so this was a happy medium to prevent BBB complaints etc.
I bet your not the only mechanic with horror stories about the mid 90's Mercedes wiring harnesses!!! I'm just a hack and this car and it's disposable wiring are driving me crazy!! Thanks for watching and commenting! TH-cam car channels need more mechanics with your experience level chiming in!!
i know im randomly asking but does someone know a tool to log back into an instagram account?? I was stupid lost the password. I would love any tricks you can give me
@Aiden Kylo i really appreciate your reply. I got to the site on google and im in the hacking process atm. Seems to take a while so I will get back to you later with my results.
Something interesting I have noticed the euro spec cars don't seem to have this problem atleadt in my experience with the r129 600s Maybe this was only a usa requirement for the biodegradable wiring. Also interesting I noticed on the mercedes only the important wiring seems to have this problem like the injection harness, throttle bodies and starter harness. The main harness for the accessories and what not are always fine
@@cassidycarcave2781 well maybe you can fill the huge gap between us normal shade tree tinkerers and Hoovie (who I like but he doesn't wrench) and Tavarish who has even wilder ambitions
I actually replaced the wiring one by one and made my own harness on one side, after the mechanic had told my dad that the harness was very expensive. now i suspect the other side is going bad, since i got the dreaded ASR light and seems to be in limp mode. i didn't take anything apart on this, my dads mechanic did. he had mentioned to my dad that i should fix the other side before it went out. now i i have to deal with it. i could have swore, those plugged into the throttle body. are the throttle body's in the front of the car????
Not sure why Mercedes Benz thought that a biodegradable wiring harness was a good idea seeing that well maintained models from that era seem to last forever
No doubt right? Just a bad decision. I have some other problems with the car that you'll see but I believe there's more wiring in the car that is degrading! Thanks for watching!
Are all the wirings affected with being biodegradable or just the important ones like top wiring harness, lower wiring harness, mass air flow sensor wirings? I’m about to buy a 600SL from an old friend but car has not been touched for decades...
Hey Harry thanks for watching the video! Yes the consensus is it's just the top wiring harness, the lowering wiring harness that goes to the starter, and also the two wiring harnesses that go to the mass air flow sensors. The rest of the wiring in the car for things like windows and lights and such seem to be okay. Good luck on the 600SL!!!
I'm thinking heat is a factor as well that attacked wiring in the engine compartment. I have a '90 300SL and the top harness from the computer along the top of the intake manifold to all the connectors are brittle, crumbling need cleanup. I think plastic and rubber parts just can not last forever in high heat areas, maybe we need to consider them consumables..
@@billrbca I think you're totally correct. It's interesting that only some of the wires in the car degrade. Maybe a supplier that they used for certain parts that wasn't up to the task? There's more in my car that has gone bad you'll see soon...
Sir I have a 1996 c200 w202 mercedes have the same problem with engine harness. Is the replacement cable has the same poor quality like original.from the car? Or any non oem wiring harness is just better (more heat resistance) than car's original?
How much did you get the car for? I'm currently also looking at a S600 from 1995 and the car doesn't run (due to wiring) (6 hours away) I really appreciate it. Thank you very much
Hey Mike I sold it to my brother so not really a market price....Once I had it back up and running I would guess it was worth around $12K... Thanks for watching!
I'm currently troubleshooting a non-running 1998 SL600 and the wiring harness looks to be pristine. What symptoms lead you to the wiring harness as the problem? My car only has partial diagnostic communication and it's not sending power to the fuel pump relay.
Hey Sean! Mine would not run at all for the main wiring harness. Crank but no start. Then it ran, but ran like crap and threw check engine codes so then I discovered the wiring harness for the MAF's were bad (Video coming this weekend.) Thanks for watching!!!
@@cassidycarcave2781 thanks for the prompt reply. So the wiring harness problem didn't affect diagnostics communication? I'm getting no crank. Pulled the ECU's and they both look good at least with a visual inspection. Just subscribed as it will be interesting to watch you work through the issues with your SL600.
@@seanbehun5926 No I was able to hook up diagnostics even with all the bad wiring harnesses...your issue sounds like a ESZ module that controls "drive authorization" - the can bus code flow that allows the car to start once the key is turned....could also be an alarm module problem...or a weak battery...hope this helps...thanks for subscribing!!!
@@cassidycarcave2781 Many thanks, I'll keep you posted and will watch as you repair the 600. You have the right demeanor for a successful TH-cam channel. Wish you luck!
@@cassidycarcave2781 the problem turned out to be a bad Base Module. I replaced it and it fired right up. I'll keep watching your channel because we seem to have an affinity for the same cars! Keep up the good work and thanks for your assiatnce.
I know that you did this video a couple of years ago but if you are still there maybe you can answer some questions. I am looking at a 1997 SL600 that I've been told needs an engine wiring harness. The build date is January 1997. I was under the impression that the 1997 did not have the biodegradable harnesses. Looking at the different Mercedes forums they say that the SL600 has 4 harnesses in the engine compartment. The top one as in your video and a lower one. I don't know what the other 2 are. Did you have to replace any of the other harnesses on this car? Thank you for your time.
They have to be custom made by some guy that Car Wizard knows (check out his YT channel). The cost is about $6000 to hand assemble one because MB doesn't make or sell them any more.
Hey there! Thanks for watching and commenting. I bought mine from Troy at mercedestopseals.com... it was really well put together and very easy to install. Completely plug and play. I highly recommend Troy for any issues you're having with these cars as he sells other items that are known failure points! Good luck :-)
Harness was $750...new updated part but had been used. Purchased from mercedestopseals.com There can be other issues with the MAF sensor harness as well as the harness for the starter but so far just this top harness was bead on my car. Thx!
@@cassidycarcave2781 thanks for the lead to where you got your harness, and thanks for sharing your videos an knowledge! I watched this probably a year ago, but just had it re- referred to me, haha, so am enjoying it again!
What other “biodegradable” electrical veins are (or were) on that vehicle??!!! Jesus Christ man!!!! …..and I mean no disrespect Sir, but that car is a real jalopy, with all that bad wiring!!!! How much have you spent replacing all of that defective junk??!!
Back in 94 these cars sold for $123k (around $248k today) Why not replace something that could easily take a couple of hours on a weekend? I own the 95 sl500 and have had these wiring problems in the past, however the car is a slick ride, smooth as butter and hauls ass on the road.
I made my own replacement harness for my 93 10 years ago.still driving it.
Nice work!!! I had to splice the harness for the MAF sensors but didn’t have the courage to make the upper harness:-) thanks for watching!
I swear this wiring harness almost ended my career as a mechanic. Back sometime in 1999-2000 I was 18 and working as a mechanic. A customer brought in a 1995 W202 C280 for a small service including spark plugs. I changed the plugs using brand new factory parts and took the car out for a test drive. The car was running on like 3 cylinders, it had a ton of trouble codes, I was terrified. Beyond being scared I was so confused, I could not understand what I did wrong. It turned out when I unplugged the coil packs the wiring up inside the harness cover had the insulation fall off and everything started shorting out. When just looking at it appeared perfect.
We told the customer their car needed a new wiring harness and they were unable to drive out in their car They did not believe us and were sure we were conning them. They towed the car to the Mercedes dealership and they told them the same thing. The customer then argued with Mercedes and wanted them to replace the wiring for free. Mercedes said, since the customer was not the original owner, the car was outside of its warranty, and the customer bought the Mercedes from a non-franchise Mercedes dealership they had no liability to fix the car. They went on to say that whoever detailed the car before they bought it used an improper cleaner that damaged the wiring harness and it was not a fault from Mercedes. Obviously a lie.
This one car almost made me walk away from a lifetime career, I am still a mechanic to this day 20+ years later.
Final details. The car was a 1995 C280 with 90-100k miles, the car was black and parked outside in California so it is possible that the engine harness got really hot. This took place at the end of 1999 or early 2000. The customer took it to a third shop and they replaced the harness for if I remember $1,100-$1,200 using a new OEM Mercedes harness. I believe my boss didn't charge the customer for the service of plugs, oil, filter, and tire rotation. Even though he really should have charged them, he was not willing to pay anything towards the wiring repair so this was a happy medium to prevent BBB complaints etc.
I bet your not the only mechanic with horror stories about the mid 90's Mercedes wiring harnesses!!! I'm just a hack and this car and it's disposable wiring are driving me crazy!! Thanks for watching and commenting! TH-cam car channels need more mechanics with your experience level chiming in!!
i know im randomly asking but does someone know a tool to log back into an instagram account??
I was stupid lost the password. I would love any tricks you can give me
@Sincere Harrison instablaster ;)
@Aiden Kylo i really appreciate your reply. I got to the site on google and im in the hacking process atm.
Seems to take a while so I will get back to you later with my results.
@Aiden Kylo It worked and I now got access to my account again. Im so happy:D
Thank you so much, you really help me out :D
I subscribed because of the celebration after the start. awesome
Always a celebration when one of my cars runs again - doesn't always happen!!! Thanks for watching and subscribing...new videos soon!
Something interesting I have noticed the euro spec cars don't seem to have this problem atleadt in my experience with the r129 600s Maybe this was only a usa requirement for the biodegradable wiring. Also interesting I noticed on the mercedes only the important wiring seems to have this problem like the injection harness, throttle bodies and starter harness. The main harness for the accessories and what not are always fine
Like the Hoovie's shirt...found him when he posted his 500SL he got in high school with his grandma :)
He is the best! Thanks for watching the discount version :-)
@@cassidycarcave2781 well maybe you can fill the huge gap between us normal shade tree tinkerers and Hoovie (who I like but he doesn't wrench) and Tavarish who has even wilder ambitions
I actually replaced the wiring one by one and made my own harness on one side, after the mechanic had told my dad that the harness was very expensive. now i suspect the other side is going bad, since i got the dreaded ASR light and seems to be in limp mode. i didn't take anything apart on this, my dads mechanic did. he had mentioned to my dad that i should fix the other side before it went out. now i i have to deal with it. i could have swore, those plugged into the throttle body. are the throttle body's in the front of the car????
Wow. It works. Amazing…
Just asking where we’re you able to find the new wiring harness for the m120 v12? Non-biodegradable wiring harness?
well done!
Not sure why Mercedes Benz thought that a biodegradable wiring harness was a good idea seeing that well maintained models from that era seem to last forever
No doubt right? Just a bad decision. I have some other problems with the car that you'll see but I believe there's more wiring in the car that is degrading! Thanks for watching!
Are all the wirings affected with being biodegradable or just the important ones like top wiring harness, lower wiring harness, mass air flow sensor wirings? I’m about to buy a 600SL from an old friend but car has not been touched for decades...
Hey Harry thanks for watching the video! Yes the consensus is it's just the top wiring harness, the lowering wiring harness that goes to the starter, and also the two wiring harnesses that go to the mass air flow sensors. The rest of the wiring in the car for things like windows and lights and such seem to be okay. Good luck on the 600SL!!!
I'm thinking heat is a factor as well that attacked wiring in the engine compartment. I have a '90 300SL and the top harness from the computer along the top of the intake manifold to all the connectors are brittle, crumbling need cleanup. I think plastic and rubber parts just can not last forever in high heat areas, maybe we need to consider them consumables..
@@billrbca I think you're totally correct. It's interesting that only some of the wires in the car degrade. Maybe a supplier that they used for certain parts that wasn't up to the task? There's more in my car that has gone bad you'll see soon...
Have you replaced the main wiring harness ( aka internal ) if so did you do a video. Much Mahalo.
Sir I have a 1996 c200 w202 mercedes have the same problem with engine harness. Is the replacement cable has the same poor quality like original.from the car? Or any non oem wiring harness is just better (more heat resistance) than car's original?
Use a heat gun to remove the plastic
How much did you get the car for?
I'm currently also looking at a S600 from 1995 and the car doesn't run (due to wiring)
(6 hours away)
I really appreciate it. Thank you very much
Hey Mike I sold it to my brother so not really a market price....Once I had it back up and running I would guess it was worth around $12K... Thanks for watching!
Is your shop big enough ?
I'm currently troubleshooting a non-running 1998 SL600 and the wiring harness looks to be pristine. What symptoms lead you to the wiring harness as the problem? My car only has partial diagnostic communication and it's not sending power to the fuel pump relay.
Hey Sean! Mine would not run at all for the main wiring harness. Crank but no start. Then it ran, but ran like crap and threw check engine codes so then I discovered the wiring harness for the MAF's were bad (Video coming this weekend.) Thanks for watching!!!
@@cassidycarcave2781 thanks for the prompt reply. So the wiring harness problem didn't affect diagnostics communication? I'm getting no crank. Pulled the ECU's and they both look good at least with a visual inspection. Just subscribed as it will be interesting to watch you work through the issues with your SL600.
@@seanbehun5926 No I was able to hook up diagnostics even with all the bad wiring harnesses...your issue sounds like a ESZ module that controls "drive authorization" - the can bus code flow that allows the car to start once the key is turned....could also be an alarm module problem...or a weak battery...hope this helps...thanks for subscribing!!!
@@cassidycarcave2781 Many thanks, I'll keep you posted and will watch as you repair the 600. You have the right demeanor for a successful TH-cam channel. Wish you luck!
@@cassidycarcave2781 the problem turned out to be a bad Base Module. I replaced it and it fired right up. I'll keep watching your channel because we seem to have an affinity for the same cars! Keep up the good work and thanks for your assiatnce.
the hood insulation is biodegradable too ??
I know that you did this video a couple of years ago but if you are still there maybe you can answer some questions. I am looking at a 1997 SL600 that I've been told needs an engine wiring harness. The build date is January 1997. I was under the impression that the 1997 did not have the biodegradable harnesses. Looking at the different Mercedes forums they say that the SL600 has 4 harnesses in the engine compartment. The top one as in your video and a lower one. I don't know what the other 2 are. Did you have to replace any of the other harnesses on this car?
Thank you for your time.
They have to be custom made by some guy that Car Wizard knows (check out his YT channel). The cost is about $6000 to hand assemble one because MB doesn't make or sell them any more.
were did u buy the harness?
Hey there! Thanks for watching and commenting. I bought mine from Troy at mercedestopseals.com... it was really well put together and very easy to install. Completely plug and play. I highly recommend Troy for any issues you're having with these cars as he sells other items that are known failure points! Good luck :-)
1. How much was that new wiring harness?
2. I thought the problem was also with the "main" wiring harness that goes into the body, no?
Harness was $750...new updated part but had been used. Purchased from mercedestopseals.com There can be other issues with the MAF sensor harness as well as the harness for the starter but so far just this top harness was bead on my car. Thx!
@@cassidycarcave2781 that install did not look that bad at all. If that's all it is, I'm a lot less scared!
It's a breeze...if you can change spark plug wires you can do the top engine harness!!
@@cassidycarcave2781 thanks for the lead to where you got your harness, and thanks for sharing your videos an knowledge! I watched this probably a year ago, but just had it re- referred to me, haha, so am enjoying it again!
What “we are” they thinking?
Sell me that harness I can get it rebuilt in Mexico
Sorry I tossed the old one away a while back...Thanks for watching!! New content coming soon!!!
What other “biodegradable” electrical veins are (or were) on that vehicle??!!! Jesus Christ man!!!! …..and I mean no disrespect Sir, but that car is a real jalopy, with all that bad wiring!!!! How much have you spent replacing all of that defective junk??!!
Back in 94 these cars sold for $123k (around $248k today) Why not replace something that could easily take a couple of hours on a weekend? I own the 95 sl500 and have had these wiring problems in the past, however the car is a slick ride, smooth as butter and hauls ass on the road.