Car doesn't start?
 

Hmm, thanks guys i'll take a look, but could there be any other issues besides that? Just tryna list possibilities besides those

Re: Car doesn't start?
 

Might want to go over the battery connections and look for corrosion as well as checking chassis grounds in the engine bay area as well.




ps Sorry to hear you only get "laidweekly". :(

Re: Car doesn't start?
 

I'd pull the RCM and have it gone over with a soldering iron before ordering a Pulse Module. In all my time here, I cannot remember anyone having a bad pulse module.

That is, of course, after going over the battery terminal connections - and just as a 'mention', my car's battery ground cable had corroded all to hell at the chassis end - I didn't find it until I replaced the battery. $12 for a generic one at AutoZone.

Re: Car doesn't start?
 

Download the 2005 Service manual, is a long section on the starter operation and diagnosis starting on 8F-35 (page 847 in .pdf) including the wiring diagram on 8F-42/854.


This part is interesting:

"Once the engine starts, the pulse module prevents starter motor damage by only allowing the starter to be engaged until the engine is running. Once the engine fires and achieves an rpm threshold that the Powertrain Control Module (PCM) defines as “engine running”, the starter motor is automatically disengaged by the PCM through the pulse module. The pulse module further prevents starter motor damage by not allowing the starter motor to be engaged if the engine is already running."

Is that a Mercedes thing ?

Re: Car doesn't start?
 

we checked out the RCM, and re-soldered it. As for the ground cable, i will have to take a look. Is there anything else that could be the cause of this also?

Re: Car doesn't start?
 

I do not think I have seen a thread where the OP erased the original question.
This has got to be a first.
:confused:

Re: Car doesn't start?
 

Well if you look at the wiring diagram on page 854 it seems clear that if you jumper B1 to F1 on the Pulse module and the car starts when you turn the key it is the problem.

Real question: is the solenoid clicking or not ? If it is you can eliminate the whole switch circuit on the right and concentrate on the high current circuit on the left.

Triage is good when troubleshooting. Just firing parts at it only is effective with OPM.

Must admit that on my cars I usually jumper the clutch switch, never know when you'll be stuck on a railroad track with a train coming (or have to get a car home without a clutch, have been there before).

For the download challenged, the diagram is below. Note they are treating the starter motor/solenoid as a black box.

Re: Car doesn't start?
 

sorry about that, i must have changed it by accident. Essentially my car doesnt start and it makes a slight clicking noise when it tries to start. Theres no turnover though, thats the big issue

Re: Car doesn't start?
 

I'd take that diagram with a grain of salt - it has the full battery B+ going straight to ground through the solenoid switch.
Might be good for cooking a few hot dogs ......

Re: Car doesn't start?
 

That's what I meant by "black box", the starter motor is where they show a ground and the box is really the solenoid.

If the solenoid is going click-click-click then the problem is on the left. What happens is the solenoid is an electromechanical device. When the switch is turned 12v travels down the chain on the right to the solenoid where a big electromagnet (pulls about 10A) pulls in the bendix drive so that it engages the flywheel. The last fraction of an inch makes a big contact that applies 12v to the motor.

The initial surge to the starter motor can exceed 100A and if anything is chancy particularly in the battery the 12v can suddenly drop to 6v or less (normally the drop is to 9-10v and there are special circuits to make sure the ignition is kept up).

However if there is a problem the voltage can drop below 6v and this is not enough to keep the solenoid energized so it drops out, the load drops, voltage returns and the solenoid tries to pull in again.

This is why a weak battery will often go click-click-click-click instead of turning over.

Also why exactly where that reported "click" is coming from is important.

Re: Car doesn't start?
 

Awesome, thanks for the help, so what's the situation of it comes from the right side? & left?

Re: Car doesn't start?
 

Left side of diagram is the power (100A+) circuit, right side is the switch.

If it were me, first thing I'd do is listen to it. If the click is solenoidish, I connect a voltmeter to the "S" terminal on the solenoid (pin 50 on the diagram) and see if 12v is getting there when you turn the key (stick or automagic ?)

If it is, the problem is in the power side (left) down to 30 on the solenoid, if not, it is on the right.

From here I'd just do normal troubleshooting with a meter and a 12v lead. No big but might take a little time depending on how accessible the connections are. No Big.

Are things like MAF and CPS orABS issues I'd pull out an O'scope and look at signals but this is simple on or off.