Electrical Power Distribution Problem
 

I have a 1999 ML320 with a 135,000 miles. Sunday it would not start. With the key inserted and turned to position 2, only the SRS light would come on. The engine warning lights did come and the key operated accesories did operate either, ie door lock, windows. The battery is only six months old. I tried both keys, thinking it mite be the anti start circuit, but no luck. The car had been running good.

Anybody had this problem? Or any suggestions on where to start.

well first off check the voltage of the battery and see if it is good. 12.6-12.8 is good.

Do the lights come on very bright?

That truck uses a relay to turn the power with the key on. Called a circuit 15 relay.
Take a quick look at your under hood fuse box & find that relay....try switching with another relay with that part number.

Additional information, after not being able to start the car on Sunday. I went to tow it home, but it cranked up to my surprize. The next day it started fine in the morning and I drove it around for several hours. I then stopped the car at the MickeyD and it would not crank. When I got out of the car I used the remote to lock the car, however the car did not lock. I thought the remote was not triggering the alarm and other systems correctly, and this was causing the car not to start. So I replaced the batteries in the remote,but no luck.

Lucky, I was able to have the car towed to my mechanic and he observed how the car was not functioning. The next day however, when he went to diagnose the problem the car cranked.

Based on his observation and some research it seems like the problem maybe the All Activity Control Module(ACM). Has any had this problem and was it the ACM. How hard is it to replace the ACM?

Aam
 

The AAM plugs into the bottom of the fuse/relay panel but is fairly easy to access. More important, the new AAM MUST be programed by the dealer, Or a really good INdependent, to reflect the vehicle, and the owner's preferences. I would figure a half hour to change it and at least a half hour to inteview you and program the AAM.

I believe there is some kind of a recall on AAMs but do not remember what years are involved. The dealer should be able to tell you.

Jim in Phoenix