RKramkowski

I've scoured this forum and several other MB forums to figure out how to proceed. This is a compilation of what I think I learned and what I did to troubleshoot.

I have a 1987 260. 120k miles. Last week, it just stopped in the middle of the road. No warnings whatsoever. It's getting fuel. I've had no work done on it recently. There's no spark coming out of the coil whatsoever. I checked at the coil itself, not after the distributor. I checked the resistance on the crank position sensor - 875 ohms, right in spec so that's probably not it. I have no voltage at either post on the coil (yes, I had the ignition on). I also pulled the OVP relay. Contacts are spotless. Relay looks like it just came out of the box. And the fuse is fine. I verified with an ohmmeter just to be sure. Further, I ran a line from battery positive to the positive post on the coil. I flashed the negative post to ground. According to another post, if the coil is working, I should see a spark. No spark. That would seem to indicate a bad coil. But why no voltage at the positive coil post then? Isn't that controlled by the ECL? Could two things have gone bad at the same time? Parts are expensive and I have no one I can borrow from so I'm trying to isolate this as much as possible before spending any money. Am I missing something?

optimusprime m1

As your car got any type of alarm or immobiliser ? This is just like a problem that i had. She was fine ,i parked up at home .Then next day no start .I went through every thing i could think of .All the things i learnt after 50 years of driving and maintaining car engines.It still would not start . Time for the experts to check it out .Ended up with faulty alarm immobiliser .A couple of wires removed from my coil and all was well.Can you see the number of wires on the coil ? Reading your post you have no power at the coil do you .So it may be up line like starter switch . Then try turning all your fuses .Dont flash live wires to electric items or you can damage the ECU. To check Crank possition sensor spin engine over do you see the rev counter needle move at all..Movment is a sign its ok.

Plutoe

Assuming you are not getting dist side coil voltage, I would concentrate my efforts on the the faulty ignition control module located on the left wheelhouse

RKramkowski

I do have an aftermarket Viper alarm but it wasn't put in by me. There are two wires to each of the coil posts so there's nothing extra there. None of those are aftermarket wires. I can see the alarm wires. They're different. I'm leaning toward the module, too, because there's no power at the coil. If I can figure out how to disconnect the alarm, I might try that, too. I hadn't thought about that possibility. Thank you to both for your help so far. Tomorrow, I do more troubleshooting.

optimusprime m1

Take a picture with a camera so you know from where the wires have come from. I had this problem but i had a reading at my coil,on small wires .But nothing from it in the king wire [centre one ] And it was the immobiliser at fault The crank possition sensor sends a message to the EZL to tell it to energise the coil . So might be the EZL .I know this is in the w124 posts is your car a w124 if so what engine as it got. My w124 is m103. Alarm removal can be easy or a pain. I took mine right out after it was up an running again. Just the mater of taking battery off and go where the alarm wire takes you and remove them Can you ask some one if you can try their EZL first.

RKramkowski

Mine is a W124 with 2.6 liter engine. Unfortunately the only person I know with a Mercedes close to mine has a diesel so no EZL. I didn't think the Viper disabled spark, but maybe it does. I'm thinking to try to disable the alarm before doing anything else just to rule that out.

optimusprime m1

RK did i send you a workshop manual link ? Check your mail .I have sent it to someone. Trevor.. there is a way to check the coil it should flash mine did not it was the immobiliser.

RKramkowski

Yes, I did get the link... I'm not exactly sure where the X11 test connector is. There's one near the EZL that looks similar but doesn't even have half the pins that the manual indicates.

I did swap out the EZL and the coil, one at a time. No difference whatsoever. I don't exactly have zero volts at the coil. I actually have .95v on both posts. I figured out that I have a Viper 5900 but for the life of me cannot figure out how to disable it. The manual recommends that to install it that everything is tied in under the dash, including power which means at least disassembling the underside of the dash to even expose everything. I found what appears to be the toggle switch that is supposed to disable the alarm, but regardless of position, it didn't seem to change anything. Everything worked the same regardless of switch position. According to the manual, the Viper doesn't disable spark though, it disables the starter itself so I doubt it is the alarm.

One thing I did notice.. when I crank it and then release the key, as I release the key it seems as though it wants to start.. but obviously doesn't because I'm turning the key off. So I did check that it is getting fuel. No apparent problem there but I don't have a fuel pressure gauge to verify correct pressure.

optimusprime m1

Do you know any one that can hot wire it ? Then you know its the starting mode at fault. As for the test point your after it will give you locations of the items if you search the electrical part in the manual.I know the manual is very hard to find what you want but its all in there.Did you give the fuses a turn in the fuse box?

optimusprime m1

May be the switch as gone ,the one you turn to start the engine . I will chech some more.

optimusprime m1

RK this is the part in the manual you need google it - 07.3-0121 Testing Electrical Components Of The KE Injection. you need to put the dots in and the dash

optimusprime m1

Try another lead from the centre of the distributor .As it as power from the coil ,then it may need the king lead [centre one in distributor] replaced .Look out you have a lot of volts from the coil .Enough to put wings on your back... Then remove distributor top and check the little carbon part in the centre of the cap inside .Check it will move in and out as its on a spring.