No Cold Start in 463
Had been using my other older 280 for dirty winter work and 463 battery was flat when I went to take it for MOT. Unfortunately, terminals other way round from 280 and so it shorted very briefly - you might imagine the colour of the air round here even though husband was doing his best to help! Now won’t start from cold but once manual injection can be got going runs normally and starts from hot. My mechanic says he can’t get an electrical reading to anything and we’re about to refer to an electrician but before we do, wonder if anyone in the Club might be able to help us throw light on this starting difficulty, as I can’t find anything similar on the Forums? Otherwise, as expected should pass MOT!!! Please be in touch if you can help.. Xtn
Hi
Check the OVP relay fuse ( over voltage protection relay) in the relay board under the glove box .this relay may have one or two fuses on the top
It should like the relay on the left handside; metal body with a red top, housing the fuse(s).
Assuming it's a 300GE, if the fuses and relays are all fine and you want to check components, I would check the idle air valve (under the air filter/cleaner housing) and cold start (7th) injector, both of which are crucial to cold starts.
There is also a thermal sensor plugged in from above towards the back of the head that tells the ECU when engine is hot/cold, so if that is not functioning correctly it will affect the rest too. It can be tested by measuring the resistance across the terminals when hot/cold and there should be a significant difference, I forget the actual numbers but the procedure is out there on the www.
Thank you 2dxb - my mechanic is away this weekend but will pass on your helpful suggestions and report back to everyone. Xtn
Hope it helps - let us know what you find.
First the good news - thanks+++ to Fixwin and Rakesh - cold start issue was indeed a blown fuse as you described, so ignition all sorted. Not so good - we're left with ABS light on and no local garage, including Edinburgh Mercedes, has the 10 pin plug needed to connect to the on-board diagnostic set up that would tell us why - N.B. ABS light had come on from time to time before husband's reverse polarity episode. So, I'd be most grateful if anyone could help us sort this one - Donald's electrician is asking for ABS component location and a wiring diagram.....? What would we do without you guys! Many thanks. Xtn
Hi first thing to check is that the abs switch on the upper dash panel is in the "off" position!!! if ok with the ignition on engine running at idle gear in park cycle the difflocks and monitor what you see...ther are two fuses in a box with a black cover just in front of the battery which contain two fuses and are linked to the trailer power socket if these are blown the it will affect the abs circuit..... PM or post E'mail address for schematics of ABS system
Thanks fixwin - don't understand this instruction after in park.... i.e. what you mean re the difflocks?
Also, what does PM mean - email address is A1@xtnhmph.freeserve.co.uk. Thx again. Xtn
Hello xtnhumph,
I am sorry that I do not have access to any wiring diagram to the W463, I feel fixwing38 might have that.
One thing that could be done to reset ABS is to; whilst on idle, turn the steering wheel full lock to full lock.
If this does not work, then the connections should be checked out at each wheel sensors, your vehicle might be fitted with either three or four sensors. Your electrician should be able to work out where to locate these sensor connections and test to see if these are working, to replace as necessary.
Alternatively, Mercedes Benz can supply you with this information, they do charge €4.00 per hour for the prevaliage and are accessible from the web site on their Service and Parts portal; you do have to register on line to gain access and the it is on their WIS (workshop information system). If your garage use the BOSCH or Autologic systems for vehicle diagnostics, they can access that information from their technical department free as subscribers.
I do hope fixwing38 comes through for you here.
Cheers,
E'mail address as advised does not respond ........
Doh - that's because I've mistyped it - so sorry! A1@xtnhumph.freeserve.co.uk
Hello again - in one of those phases where everything is packing up, including computer - hence absence! Meanwhile, the ecu for ABS has been found to have water in it and hasn't responded to being dried out with a hairdryer - other checks you kindly advised suggest ABS should be working. Is there anything else to be done short of obtaining a replacement part and how/where would I find best value one? Best Xtn
Hi
before you replace the ABS control unit ( very expensive) check relay 7 and 15 ( I will send schematic to yor E mail more important find out where the water is coming from >>>>>>.most likely the wiper spindles or corrosion along the bottom of the windscreen lower frame under the rubber seal
Many thanks - will pass this on.
New windscreen was fitted after stone damage last autumn - don't know whether the water happened before this. Did have problem with screen washer - could this have been the cause? Xtn
As I have not fully followed up on your issues, my current understanding is that you may have an ECU issues.
I just wanted to add, water ingress in ECU's can do connection and hence circuitry problems. Drying out by the hair dyer may not achieve much. It is possible to have the ECU's tested and consequently repaired.
I am only aware of such service and have no idea on comparative costs.
If you are interested in going that path let me know and I can send you links to those sources.
Cheers,
Hi, the OVP relay that was mentioned earlier in the thread is also part of the ABS control circuit. A symptom of a fault in this rerlay is that the ABS light comes on. The frustrating thing about these relays is that they develop an intemittent fault rather than just failing completely. If you have a combination of poor cold starting and the ABS light is on then you might want to try a replacement OVP relay.
Yes pse Rakesh - will be pursuing all options. Xtn
Most interesting thanks bigblock - the ABS light would come on randomly for short periods before the cold start problem but is now on all the time and ABS not working even though the cold start now OK. The water we've found won't have helped, of course!
Will let everyone know how we progress - most grateful for such interest and help. Xtn
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Many thanks Rakesh and Fixwin38 for your fast response - will report back soonest. Xtn