w140600sel

Hi

I have decided to take the plunge and have just purchased a 1993 600SEL here in the UK a few days ago. It is quite a rare sight over here. I also own another smaller car and I owned several other classic cars namely old Peugeots, old Datsuns and before I had purchased this 600, I had an LS400. The LS400 was a very refined vehicle but to be honest I found very boring. This is my very first mercedes. I love the way the car rides and looks and is very imposing.

Anyway, I would like someone to help me with the following problems I have with the car. I am an amateur mechanic/hobbyist and have worked on my other simple cars in the past so can tackle easy jobs with no real issues.

1. The battery went flat on me. Subsequently, I have discovered that the REST function (heating) in my car does not switch off even after the car is switched off for at least 2-3 hours. I have pressed the REST button but this just briefly switches off the heater for 1-2 seconds and then the heating again comes on. If I hold the REST button the heater switches off, but as soon as I release it it goes back on again. So it basically won't switch off. Another thing is that when I switch on the car and set the temperature to degrees celsius and when I switch off the car and the REST function switches back on automatically the degrees change automatically to farenheigt. What does this mean, is there an issue with a relay somewhere? or the control unit or something else?

2. I have run the heating control diagnostics and this has thrown up codes 74 and 75.

74 - Coolant Circulation Pump (A31m1) - Continuous short or open circuit
75 - Coolant Circulation Pump (A31m1) - Intermittent

So my question is would this be related to the REST issue I am having? i.e. would replacing this pump also get rid of the REST issue I have mentioned above?

I have reset the codes but no use.


3. When I purchased the car, I had got it for a good price. At the time the seller had mentioned that there was an issue with the car at higher revs or sometimes when the car is idling. I purchased the car knowing that and the seller had knocked several hundred pounds off for that problem. The issue is that the car hesitates when accelerating hard, mainly above 4k rpm and its like a sudden jerky movement like the engine wants to cut off. Its almost like the engine stutters. Similarly when the car is in idle, the revs are mostly rock solid. But however, sometimes every 5 mins or so the revs drop and the needle fluctuates between 300 and 800 rpm quickly for about 5-10 seconds before idling nicely. Can someone shed some light on this? Would this be a MAF related issue? I have also noticed some clicking sound near the throttle body at the left bank of cylinders - is the throttle body likely to be suspect?

Hope someone can shed light with these issues. I am a real car enthusiast and am willing to do most of the work myself but have never worked on such a complicated machine before.

Thank you

w140600sel

Hello

I have eliminated problems-

1-Faulty aircon controls so replaced unit
2- No need of this pump in our cold weather

I still need help with point 3. Can someone please shed some light if possible.

Thanks

burgca

Was the original wiring harness replaced?