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Dreaded “3 Bars”

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Dreaded “3 BARS”Once ok, but know it has become too regular an occurrence.• Seems to happen only while the gearbox is downshifting either in “soft touch” or manual.• Weather conditions in all cases was dry and mild (Spring like)• Has not been following any kind of pattern, but has become more frequent• In all cases the engine was at normal operating temperature• It is either on the slowing down or once I had come to a stop.• No other lights on such as traction control or check engine, although they sometimes appearHistoryJust shy of 148,000 km, no major work performed everything original, car in not driven hard hence a 4.09 L/100 lifetime (logged every fueling since purchase). Recently cleaned the EGR and lubed the clutch actuator (aka the Duck method).Something that has plagued this car from the beginning is that the traction control light comes and goes like it has a mind of its own. I start the car and before I move it’s on and stays on, turn off the car wait a couple of minutes, restart car and is gone and I hadn’t moved an inch. I get the same thing with the check engine light, start the car and its there turn it off and restart and it’s gone. :huh: Spooky!QuestionsI have read most of all the posts and links relating to the 3 bars, but I will still ask some questions as some of the posts are a bit dated and or vague, such as check everything including topping up the windshield washer fluid. 1. Has anyone had the same symptoms and what solved it?2. is this a clutch issue?a. Does the clutch need adjustment and at what point should this be done?b. What is the typical life of the clutch (non aggressive hwy driven)?3. What codes should I be looking for and does the Scan Gauge show these codes.4. Is there any symptoms or indicator lights I should be looking for.

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andrew lee in Newmarket did a good job resolving my issue of 3 bars - he as all the good diagnostic equipment that is needed and from what I can tell is not just a new parts installer like some dealers can be.

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you might want to give the clutch an adjustment. i had my 3 bars around 130km. i did the cleaning an adjustment an it went away. i still have a code for transmission though. lots of the guys have found a blue wire in the harness gets broken an causes problems. some where around here is a big thread i started about this.

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Posted (edited) · Report post

Definitely your clutch actuator needs adjustment.

The computer (clutch) will adapt to clutch wear, but there is only so much it can do.

A mechanical clutch actuator adjustment is required followed by a trip to the dealer or someone who has a star machine to "teach in the clutch".

Here is a link as to how to do the adjustment.

http://www.evilution.co.uk/index.php?id=331

Caution: use plenty of penetrating oil on the 3 bolts.

Recommend that you disconnect the battery (you have the radio code?) and electrical connector on the actuator. Then remove actuator from car and inspect the clutch fork for holes and cracks, then put a dab of break grease on the actuator ball before reassembly.

As to your ABS light, look for cracked reluctor rings, usually the rear ones, if the rings are good.

Get a wheel alignment done as close to Mercedes as you can, then go to Mercedes to get the steering wheel position sensor recalibrated.

The car may have more ABS traction control issues on the way to Mercedes to get the recalibration done that's why I said to keep the drive short.

Canman

Reason for edit:

Correction as per Tolsen's post.

I still think adjusting the actuator will fix the problem, it worked for me.

The original poster said the weather conditions were dry, the chaffed wiring usually acts up in wet weather.

Canman

Edited by CANMAN

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If you haven't checked it for chafed wiring, do so now.

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3 bars indicate there is a shifting system fault. Usually caused by chafed cables if intermittent. Both Evilution and FQ101 provide further guidance. I believe both advise you to check gear position sensor among other things. Gear position sensor is not used for shifting, it is only a backup for diagnostics. A faulty gear position sensor may cause 3 bars but the car will shift and drive normally. Gear position for gear shifts is sensed inside gear change motor.

Clutch bite point is fixed and cast in stone until next electronic clutch adjustment. ECU does not compensate for any clutch wear. Clutch has built in automatic mechanical wear adjustment. You will feel when clutch or clutch actuator need be attended to - a bit similar to an untrained driver operating your clutch.

Posted Image

Sectional view of the Getrag gearbox.

FQ101 link: http://www.fq101.co.uk/how-to-guides/fortw...the-3-bars.html

Evilution's site was down when I made this post so can't provide any link.

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I guess after 148000 km its time to have the clutch adjusted, at the same time I'll look into any chaffing of the wires.Thanks for your input and I'll let you know how things go.

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Hello Hello... Havent been on this site since the spring.. been a very busy season this year (I build Koi Ponds) Last time I probed you all for usefull information was due to the wifes starter issue. finally got the new started installed in spring... all is great. So now we are into this 3 bar thing.. have repaired the wires at the scoop using DEI tape from performance improvements. Took out the clutch actuator and cleaned/re-greased the unit, added a tie-wrap around the boot to help prevent crap from getting in there and adjust the clutch manually to the car. Also checked connectors and added dielectric etc... Also changed the grounds to 1 gauge cables.. She has had the 3 bars come on at 120km in 6th on the highway, as well as shifting down into first. I am seeing codes for both the speed sensor.. p0702? as well as ABS controller p0500 i think. ABS/TRAC lights are off at startup, but do come on after 15min of driving. Thinking next about changing the gear position sensor..? Mercedes advisor said its prob just clutch adjustment but I dont see how that would effect the car when its in 6th and not shifting... Any other thoughts I havent read in other 3-bar posts?Brent

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Clutch/transmission error. Three horizontal bars where the gear display should be.Sometimes minor, often serious, many possible causes.

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Ah, OK! Uncle Glenn did the actuator and reprogrammed the thing 2-3 months ago. Hopefully that will keep them away.

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brent glad to see you got the no start fixed.id say your abs/ traction control would be from a broken abs ring. it might be just a hair line crack in it right now so the computer will come an go till it fully opens up an the lights stay on.

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Did you ever find the solution to this problem?My abs lit flashed at me today on my way home. It then went solid and the car behaved as if it were in neutral. That's when I got the 3 bars. I shut off the car and restarted it. It ran fine and shifted normally for the rest of the trip home. The only thing is the abs light was continuously lit the entire time. I checked the code and got the p0702.Anyone have any ideas?

Edited by Z1K

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he had to change the transmission gear position sensor. mine will do this from time to time now also. may be fine for months an then the code will pop up for a few days an then be normal again. it will be next to change out in the summer

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Gear position sensor is not used for shifting, it is only a backup for diagnostics.

The position sensor (encoder/potentiometer) you're talking about gives feedback to the motor controller (drive) about the position of the drum cam that controls the shift forks, so it is an essential component of the mechanism. Without knowing where the drum cam is, it's blind. If it's intermittent, yes it would still work, as there is dwell in each cam profile so it can be out several degrees of position and still be locked in gear... but it probably throws the fault to indicate "get this checked out".-Iain

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Gear position sensor was the 3 bar culprit after showing P0702. It was like $130 and took 10 seconds to swap. I did have the chaffed wire issue as well, but only after replacing the sensor did the issue go away. I also had cracked rings... they were not replaced until this past weekend and the three bars never came back after changing the sensor.

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I think the chafed wiring may be the culprit with me. (Seems only a problem when the roads are wet) Happened again this morning and almost stranded me on McCowan Rd. Managed to get her going again so I pulled the car inside for the day at work. Once the car dried out all was well and the traction control light went out. The roads were dry when I left and the car ran as it should. I'll also have to look into the sensor if the wiring isn't the culprit. Thanks for the suggestions.Hopefully I can find the time to get it fixed up soon. This couldn't have happened at a worse time.

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Ok so no Chaffe d wires. I pulled all the plugs related to the transmission and pulled the harness to the top of the engine for inspection. I can only drive the car for about 10kms before the 3 bars now. So what's my next step? Gear position sensor? How do I go about testing it in case I don't need to buy a $130 part? Thanks

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I had the three bars nearly a year ago, and it was chafed wires. The issue was fixed satisfactorily by Andrew Lee (see wiki entry). You're in Courtice, though if you go up McCowan regularly, driving to Newmarket to Lee's Autohaus may be a reasonable option (if you don't want to go to MB). I am sure he'll take a very close look at the problem and give you a good diagnosis for a fair price.

Of course, if it's the GPS, the part will have to come from MB regardless. Their time is much more expensive, though.

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If its not chaffed wires I would go with the clutch actuator adjustment, see Evilutions website.Be sure to disconnect the battery first. Then remove the actuator entirely and inspect the fork for wear/hole.Be careful with the actuator mounting bolts, they have been known to break, use lts of penetrating oil.Adjust as pe Evilution and then go to someone with a star machine to teach in the clutch.Canman

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[i lubed and adjusted the actuator a couple months ago. I took it off when I was checking the harness today and all looked well. So I lubed the rod and reinstalled it as per evilution.Afterwards I took it for a 10 minute drive and all seems well. But that doesn't seem to matter though as it is pretty intermittent. It was dry today and it happened twice on my way to the shop to check it out. Usually as I'm getting off of the highway. I'm wondering if the problem occurs when the car reaches full operating temp.Thanks for the suggestions so far.

Edited by smart142

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Change your gear position sensor. I dont think you can test it.

Edited by AHZELA

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