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Thread: Loom

  1. #11
    Join Date
    Feb 2011
    Location
    Lewes
    Posts
    736
    Have you had the codes read on a suitable diagnostic platform? Something like a STAR or a Delphi? Although your car should be fully compliant with the OBD standard, there might still be some things which are Merc specific and won't show on a generic reader.
    Do you have the car at home or is the car sitting at a garage waiting for you to take it away?

    Did you get the alternator from Merc or just via a local garage - Smarts are very picky about which alternators they will work with.

    Crank position sensor can throw some really peculiar errors, mine went haywire and would cut out when just driving along - leaving you to try an coast to the side before you actually stopped. Then you would have to wait a variable amount of time before it would start again. I even had a Star connected up to the car and logging data when it went wrong and no code was produced. made it very difficult to diagnose, but for the cost of a new sensor and the time to fit it. It proved to be the item that was faulty, because the car worked perfectly well after it was replaced.

    John

  2. #12
    Join Date
    Dec 2004
    Location
    Wells
    Posts
    1,543
    Crank sensor or dry joints in the SAM unit (fuse box) and a new mechanic! Is the MB specialist still nr the main dealer in Hove? Going back a few years now but the owner used to have smarts himself (and a mini moke!) so may be worth a call.

  3. #13
    Join Date
    Oct 2009
    Location
    Bury Lancs
    Posts
    157
    It was decided that the loom was the culprit for the demise of my previous 451 ..... I gave up with it.

  4. #14
    Join Date
    Mar 2012
    Location
    Burnley
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    1,417
    Quote Originally Posted by EmilysDad View Post
    It was decided that the loom was the culprit for the demise of my previous 451 ..... I gave up with it.
    Hmm. I scrapped one with the same fault and I had checked out all of the loom in it, it was not at fault.

    I don't think yours was the loom but you got shut before I could prove it.

    It would be nice to get to the bottom of that particular fault on a 451 but I don't think the 450s ever had that problem.

  5. #15
    Join Date
    Apr 2015
    Location
    worthing
    Posts
    9
    No sound at all when you turn the key, but all the lights come up on the dashboard. It wouldnít start for an hour or so then start again, but now wonít start at all.

    Unfortunately itís now at Mercedes, theyíve run diagnostics, tested the SAM unit everything works. They are 90% sure itís the starter motor as the one that was fitted wasnít a genuine part. How true that is I donít know, but they said that because the car was working and it would just cut out it was the starter motor overheating.

    I will mention the crank position sensor tomorrow to Mercedes to see if thatís been explored. Sadly I was put in a position where no garage in my area wanted to touch my car as soon as I said it could be a electrical fault. Itís had a new starter motor, alternator and the SAM unit was sent away to be tested as well (which came back with no issues).

    Iíll keep you all updated. You guys have been great and itís nice having a community of fellow SMART enthusiasts. Thank you.

  6. #16
    Join Date
    Feb 2011
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    Lewes
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    736
    I am sure others will agree that there is no way the starter motor overheating could be the cause of the engine cutting out.... Sounds like they don't know what is causing the problem and have decided to blame something (the starter motor) because it is not a genuine part.

    Starter motor being faulty would prevent the car from starting - easily proved by bump starting the car, or replacing the starter motor with a known good one. A faulty starter motor could be tested by powering it direct from another battery. I wonder if they have tried setting the clutch bite point as that sequence has a "start the engine" section in it that would show if the ignition switch was faulty.

    It is possible the relay under the left hand seat is faulty and not switching power to the starter when the key is turned.

    Was it Mercedes who said it need a new loom? Do they know that the starter motor is triggered by a useless spade connector? - If it was, then another reason as to the fact they don't know what's wrong if they blamed the wiring and now the starter motor!

    John

  7. #17
    Join Date
    Apr 2009
    Location
    Ecosse
    Posts
    3,782
    Quote Originally Posted by Heinkeljb View Post
    I am sure others will agree that there is no way the starter motor overheating could be the cause of the engine cutting out.... Sounds like they don't know what is causing the problem and have decided to blame something (the starter motor) because it is not a genuine part.
    I didn't want to be the first to come in on this but have to agree. I can't see how a starter motor can have any effect once an engine is running. Your later point about the spade connector is also valid.
    Something that crossed my mind some time ago is that with the age our cars are now, I doubt that there can be many 'technicians' in the MB/smart network left who received the training that would have been circulated through the dealerships at the time of the cars' release. Looking at the 450's withdrawal from production - that was some 13 years ago.

    Quote Originally Posted by Heinkeljb View Post
    Starter motor being faulty would prevent the car from starting - easily proved by bump starting the car, or replacing the starter motor with a known good one. A faulty starter motor could be tested by powering it direct from another battery. I wonder if they have tried setting the clutch bite point as that sequence has a "start the engine" section in it that would show if the ignition switch was faulty.

    It is possible the relay under the left hand seat is faulty and not switching power to the starter when the key is turned.

    Was it Mercedes who said it need a new loom? Do they know that the starter motor is triggered by a useless spade connector? - If it was, then another reason as to the fact they don't know what's wrong if they blamed the wiring and now the starter motor!

    John
    I suspect though that the car in question here may have multiple issues. You've more or less covered the non start issues but some of the symptoms mentioned are compatible with a flat/failing battery - but yet it is capable of starting the car. If this were my car I'd go straight to the earth leads - especially the ones in the engine bay that just rot away. Failing cables there - or elsewhere - could also cause the engine dying symptom - but that is the calling card of a failing CPS. Were it not such a PITA to get at, I'd replace the CPS as a matter of course (unless I found a seriously bad earth/main power lead).

    The biggest problem here is that 450s are so damned awkward to work on and because of that are shunned by other garages, MB/smart dealerships lack the experience of good indies and good indies appear to be thin on the ground. While I still have my 450 I have moved onto a 20 year old truck. I could have changed the CPS on it in the time it's taken me to type this post - enough said.

    BettyBoo: you've gone a fair way into this already by eliminating the SAM as a culprit. Persevere, do the simple and cheap stuff first and by a process of elimination you should solve all the problems. Consider finding a garage that will do good quality work for you if you provide them with printed guidance from FQ101 and/or Evilution. If they can at least be made aware of what they are looking for and where to find it, you may overcome their reticence. It is just a car after all - just one that hides its components somewhat awkwardly!

  8. #18
    Join Date
    Oct 2009
    Location
    Bury Lancs
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    157
    Quote Originally Posted by Mjolinor View Post
    Hmm. I scrapped one with the same fault and I had checked out all of the loom in it, it was not at fault.

    I don't think yours was the loom but you got shut before I could prove it.

    It would be nice to get to the bottom of that particular fault on a 451 but I don't think the 450s ever had that problem.
    Phil Ball was pulling his hair out with my car as he'd swapped various bits & pieces from my car to others & vice versa and his suspicions were the loom - it was obviously p***ing off that he couldn't get to the bottom of it ..... the car was then taken miles away (there was an unintended pun in there ) and it was time to throw the towel in with it.

    I do regret sending it to the second garage & feel a bit ripped off ..... I should have stripped it myself & transferred some of the nice bits to my current Smart.

  9. #19
    Join Date
    Nov 2004
    Location
    North Weald, Essex
    Posts
    169
    A failed or failing CPS wouldn't stop the car from turning over from my experience, it just stops it firing up.

  10. #20
    Join Date
    Nov 2004
    Location
    North Weald, Essex
    Posts
    169
    Quote Originally Posted by Heinkeljb View Post
    It is possible the relay under the left hand seat is faulty and not switching power to the starter when the key is turned.

    John
    I don't think this car has these relays as it has a SAM unit not the older ZEE.

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