Last few days, clicking sound at start, recycled and started fine. Noticed that locking system activates and goes through 2-3 cycles now. (locking and unlocking doors)not prior to problem...new glows etc. any ideas.........thanks

marketwize2003,


What model car? What do you mean the locks cycle two or three times? Is this on their own or is this how many times they cycle before vacuum is used up? Did you install new glow pulugs recently?

I take it the problem you have is that the key, in the start position, does not always activate the starter. IF this is the case, the problem is relatively common and a search will turn up quite a few possiblilities, mostly with either the solenoid, the key switch, the battery voltage or the starter itself. Once you know which it is, the solutions differ somewhat.

The locks are a different story and I honestly did not understand the problem based on your description, or the significance of the glow plug comment. Who replaced the glow plugs? Did you do it yourself? Once again, knowing the model car and year will help as the glow plug systems changed a few times over the years.

Good luck, Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

sorry, car is 1983 300sd, glow plugs replaced at local dealer 4 months ago. Often (not always) when starting, locks go from locked to unlocked at least 2 times. That is when I have difficulty starting. Locks are fine otherwise.

marketwize2003,

I am not sure of the set up for the door locks in that car. At some point Mercedes changed from a system that stored vacuum produced by a vacuum pump driven by the engine to operate the locks to a system that uses a small electrically driven pump. I am not sure when this change was made on the body you have. I am pretty sure the later W126 bodies had the change and the the little box was located in the trunk.

If the electrically driven pump is the system you have, it seems to me the ground could be "unstable" on either the key switch or the vacuum locks or both and the system is being turned off and back on in mid stroke. Not really sure what that does to the logic in the little box with the vacuum pump and motor, but I can imagine it makes the system decide the lock is either open or closed at that instant. If the position indication signals from the doors with key locking capability then report some other position than the assumed on the logic board reports an error. To correct an error the system may cycle the locks until the hardwired logic and the actual position data coming back from the locks agree. I would check the ground connections on the battery as it affects both the locks and the starting issue. Then I would check the connections at the module to make sure they are "stable" and correct.

If the system is the vacuum storage concept of old, I am not aware of any mechanism to cause the cycling you describe and ci cannot imagine one very readily like I did above. The vacuum shut-off signal comes from the starting key operated switch, but I cannot figure out how this item's position or condition can cause the door locks to do anything. If the locks did not work at all and the car's engine was not shutting off when you turned the key to the off position, I would suspect a major leak. But that is not what you report.

Good luck and I hope someone else pipes up soon. Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)