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When I turn on the engin, sometimes the ABS and 2 lights next to it turn on (see pic)
. They turn off after restarting or after a while driving. Nothing noticeable to the driving, but strange. Is this to be solved?
I finally got to do a scan on the truck.
It said about a left front wheel speed sensor. The electrician erased the fault and advised me to drive (over 60km/h) and thought the fault might pop up again. So far it didn't. The 3 lights are also off, didn't turn back on again.
When I brake the triangle light with exclamation mark turned on (flickered) 2 times, but I believe this is for the brake pads which might be worn?
I've had a rescan done and attached a pic of the reading. It's an intermittent fault. Best would be that I change the front left wheel sensor I suppose?
I thought the sensor was the only connection,i didn't know that there was connections before as well. I do not want to disregard Jim's advice at all, he has the best miraculous advice I've ever seen. I must have misinterpretated it. Anyways, it's ordered. But when installing it, I definitely will check any wiring.
The exclamation mark is usually telling you traction control/ ESP/ 4ETS is being activated. It shouldn't happen.
It likely means the wheel speed sensors is receiving errand signals, or perhaps different wheel sizes, something like that.
Sometimes junk gets between the wheel speed sensor and the little latter thing going around your axle that the sensor picks up on. Could also be the wiring leading up to sensor or the connector in the wheel well.
You can hook up an oscilloscope to the sensor and spin the wheel and see if the signal is coming through clear to diagnose where the signal is getting corrupted.
Keep in mind while all those lights are lit up ABS, ESP, traction control and 4-ETS will not work, so it can effect driving.
I doubt it matters, but personally I'd go with aftermarket.
I read once that the OEMs fail so often some people were opting to keep a spare in their truck, lol.
I keep a spare now too but haven't had mine fail in years, and I put in a used one! Lol.
Just make sure you get the one for your year vehicle because they changed it in 2000 or 2001 to just a two wire and not a 4 wire.
Btw I was suggesting that it may be the problem not the problem.
Another thing that wears out on these trucks is the ABS motor brushes. Theres a video on YouTube on how to replace them however I just keep a spare motor I got from the local pick and pull.
Also a real common problem I've had on these trucks now that they're getting old is bad relays and bad connections on the relays/fuses from oxidation/arching on the contacts.
Often times the problem can be real tricky to diagnose because just the act of opening and closing your drivers door or driving around can knock it back into connection. Lol.
I had a bunch of phantom problems then I cleaned all the contacts on my related relays and fuses with some synthetic steel wool and they went away. I also have had a couple of those black relays go intermittent or fail outright over the years. I keep spares now in the fuse box.
SpenserM, I just got a full diagnosis on persistent problems with relays and fuses over several years...until the car just completely shut down.
My horn would stop working..and wiggling/replacing the horn relay would sort it out for a few weeks and then back to square one.
Turn signal relays blowing at randon intervals in hotter months.
ABS motor fuse blew, and later ABS relay below as well...
Once, the starter relay blew
Then once, the fuel pump relay
and on and on...the fuse box was just driving me nuts over the last 5 years...
Then, this spring, ABS/ESP lights would flash intermittently...then Transmission started locking up in limp mode intermittently...then, engine started shutting down intermittently….until everything was no longer intermittent....the truck set itself permanently in limp/rough idle mode...as soon as I start the truck, the engine would just go into rough idle, no effect of gas pedal, and transmission locked into P.
I had it...I pretty much, thought this was the end of the road for my W163...got it towed to dealer...dealer gave up on it...said forget it..it has some major electrical problem..not worth diagnosing and going further with such an old vehicle..
I was heart broken...
I was then referred by someone to a specialist electrical mechanic....after 4 days, he narrowed it down. The whole fuse panel was the culprit. He replaced my whole fuse panel (and transferred over all the relays and fuses)….at least 10 pesky and nagging electrical problems from the truck disappeared after that.
A new replacement fuse panel is getting harder to find...some dealers told me, it is no longer available...some said, it could be order through special order..
Anyways, we found a salvaged fuse panel from a W163 that was totaled at just 60,000 miles...and decided to go with it.
My truck is back on the road at 19 years/231,000 miles...with no more electrical problems...all pesky flashing idiot lights are gone...horn is working..and all other intermittent electrical problems are gone.
WATCH THAT FUSE PANEL...it has reached EOL on most of these vehicles...
Cheers, that's some good advices that you're giving out.
I'm gonna go for the aftermarket one myself, lol.
Good to know about cleaning and checking the fuses and relays. Maybe some contact cleaner spray would do some good as well...
Yeah that's a good story and I'm glad it had a happy ending!
I basically had the same problem and funny enough it started with my horn relay too. I think it's cause it's one of the least used, I dunno. I didn't end up taking drastic action until my truck started randomly not starting. It was always so frustrating before I figured out it was a chronic issue with the contacts because I'd slam the door in frustration and the truck would start up!
Dealerships are hilarious with older cars. When I was younger I assumed they'd be the best at repair of their own cars, especially more expensive foreign brands and would only get better with ~10-15 year old cars due to volume, practice, experience, access to the history of that car and access to Repair Bulletins/special tools/ and MB diagnostic equipment.
But they're not. Lol. Especially with problems related to age or problems more difficult to diagnose. They like to just throw parts at it, and plus the truth is over time more and more owners out of warranty take their cars to independent shops to save money.
What you imagine is some tech who's purview was that exact model since new and knows every part, module, wire, bolt and possible fault and just has to hear the symptom to know the diagnoses. Not usually true.
The experienced techs probably dont wana work on old stuff, or moved on, or just aren't that good at actually fixing stuff.
One time I took a GMC Jimmy to the dealer cause I couldn't figure it out...they say injectors...I say are you sure? They say ya!
.....nope doesnt fix it...
fuel pump they said next...
I said well if youre gonna throw parts at it I'm not paying for stuff I don't need if doesnt fix it...they said np... no fix lmao.
...then they replaced at least one maybe two expensive items...they say it's fixed...
I go to pick it up and not only is it leaking gas now (lol) it dies in the parking lot, same problem. I was super pissed and only had to pay for like 1/4 of the repairs after they fixed the leak.
*******s weren't even test driving after they threw random stuff on it.
I go to a different dealer, they literally do the same thing, do an ecu or something this time, except this time I go to pick it up and it has a major leak in a coolant hose in the parking lot...they refuse to fix it because the hoses could all be old and about to crack...it was only 10 years old and in good condition!
Still doesnt work so I pay for the part only.
I take it to an indy and in one day he figures out it's a broken wire on the harness for a fuel injector.
And yea some 2001+ MB, I believe cars, actually had bad fuse or distribution boxes that are just bad.
However I think one of the culprits is when they switched to those tiny micro bladed fuses. Way smaller surface area. I've seen similar problems in early 2000s jeeps.
Contact cleaner is good, but not usually strong enough. You need physical debridement of the oxidation because its thick. And it's hard to clean the little contacts for the fuses and they have such a small little contact area. I used sand paper and jammed repeatedly down in there. I think they make special files for the job too, I'd get one of those.
What I did after the sanding and contact cleaner, because the oxidation kept coming back is replace my fuses with new ones, same thing with many relays.
Then I coated the contacts in "conductive grease". I also fixed the clips that hold the lid down and greased up with normal insulating grease the seal that goes around it. Oh and I replaced the E box fan...I assume it keeps the moisture and obviously heat level down. Now no problems for a couple years.
But yah I should have just replaced it with a low milage nice unit. Lol.
The dealership network definitely has the best tools at hand for diagnosis and troubleshooting, but I am now convinced after this episode, they don't necessarily have the best mechanics & the right attitude around servicing older cars. It is sad, that dealerships would disown older cars for complex repairs.
Reviving the W163 beside, me and my primary care indy mechanic both were extremely curious to get to the bottom of why the truck was shutting down like this. We sent it to the dealer to get the exact diagnosis.
Dealer diagnosis was definitely more in depth than just fault codes, and it said, the main voltage on the car electrical was fluctuating and lower than what it should be. They did not want to go further into finding the cause...they recommended starting off changing all the main wiring (cost $2500) and then troubleshooting further....
If I were the shop manager at the dealership, I would in fact be curious too, to learn and get to the bottom of such problems rather than shooing the car away, as too old and too difficult to fix. It would be a great learning experience for the dealership and the mechanics working in it.
I was not very hopeful from the specialist indy mechanic where it went next, but I at least wanted to understand the root cause.
He not only pin pointed the root cause, but also came up with a definitive repair plan, and it was all not that difficult for someone who knew the trade of electrical troubleshooting.
This indy was 100% confident, the oxidized/corroded fuse panel was causing all the systems in the car to shut down...and the low/fluctuating voltage on the main electrical line. Since, I was going to pay him decent money for this work, he said, he was going to go ahead and test all the electrical wiring from A to Z on the truck...and he found 3-4 weak spots that had signs of corrosion/moisture damage over all these years. He took care of fixing all that while at it. My car's entire electrical is kinda refurbished at this point.
I am extremely glad to have my w163 back on the road with all the pesky lingering electrical problems eradicated by a single fix.
My fuel gauge has also been off for a few years now, and reprogramming the cluster and recalibrating the fuel pump float were not helping. It was a dead end...guess what, the root cause was the fuse panel...the fuel gauge is back to reading correctly after the fuse panel swap.
I also learnt a few additional in depth things on the ML's electricals while getting it fixed..that are worth sharing.
I saw the indy mechanic's diagnositic paperwork and it seemed to suggest, as per MB, a swing of more than 0.4V on the car's electricals is considered out of spec.
All the car electricals run at 12V, and so a swing of 0.4V is not much tolerance.
Oxidized/mildly corroded fuse panel can easily cause this.
I opened my old fuse panel up...it is a sandwich of 2 plastic panels...all the fuse/relay connectors on top and CAN connectors at the bottom. Inside, there is not much...lots and lots of copper plates/connectors isolated by plastic molded separators that are molded right into the plastic panels.
It is impossible to know by visual inspection that these plates are oxidized/corroded. My guess is, the indy specialist mechanic isolated the fuse panel and then must have run some resistance tests on it to conclusively deduce that it was not letting current/voltage flow within spec.
Cheers, that's some good advices that you're giving out.
I'm gonna go for the aftermarket one myself, lol.
Good to know about cleaning and checking the fuses and relays. Maybe some contact cleaner spray would do some good as well...
If you're getting aftermarket Brake Light Switch, be ready to replace it again in 6 months.
The person with 30 posts whose advice you're blindly following without him pointing to any evidence versus Maj. Dundee who is a veteran expert and mechanic on these trucks and told you exactly what to test for.
The person with 30 posts whose advice you're blindly following versus Maj. Dundee who is a veteran expert and mechanic on these trucks and told you exactly what to test for.
Good luck!
For now I'm following Maj. Dundee's advice, I was just telling you who talked about this. I'm not touching the brake light switch yet. First I change the speed sensor, check the wire that goes to the module (wherever this one is) and then I'll see how it goes.
And yes, Maj. Dundee's advices are precious and priceless, more like amazing...!
04-15-2019, 10:29 PM
