W124 - Ticking under passenger side dash when OFF only... any ideas?

Following up on my prior thread.... I drove car 40 minutes home, went to start and just cranked over... let it sit for two hours, went to start, the little box mentioned in prior post clicked away as I attempted to start... started, died, started , died, no more starting...

btw, on the way home I tried the cruise control and it worked.

Could it be this little box? Does the whole thing have to be changed? Not little, its $1K new ......

any ideas? I am car less again in 60 days.... Fuel pressure regulater had been changed on the last no start problem it had 30 days ago, but nothing else was spotted as rotting away..

thanks

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1995 E320 smoke silver / parchment

I read through the other thread and have a few observations:

Unsure why this would be ticking constantly

This is a M104 engine with HFM and EA. The EA module in effect is the cruise control module, but also handles the operation of the entire throttle motor (Electronic Accelerator, Cruise Control, Idle Speed Control, usually abbreviated EA/CC/ISC). I am unsure of the location of this module, it very well may be what is clicking.
IF that's what is clicking, this may well be why the engine isn't starting properly, although if it eventually starts, idles and drives OK (and the cruise works), one wonders why the problem magically clears up and everything is fine and no check-engine light at all.

My gut reaction is that if this clicking is related to the problem starting, and it's all related to the EA system, MORE than likely it's related to the well-documented engine wiring harness problems that this vintage of 104's are known for.

It would be best to have someone monitor if there is a fuel pressure problem when this occurs, or spark/ignition or fuel triggering problems, etc, and also do a quick-check for diagnostic trouble codes in the major engine related subsystems.

Gilly

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Thanks for taking a look... resolution sounds more complicated for me at this time due to time / work .... Wiring harness head been changed a few years ago per documentation that came with the car and that MB service printed out for me.

Today stuff happened fast so don't remember the details, but I do know the ticking started when I turned the key to start and as I was cranking the starter it clicked away.......

I will access the situation tommorrow ...

thanks again for the detailed explanation.

edit "This is a M104 engine with HFM and EA. The EA module in effect is the cruise control module, but also handles the operation of the entire throttle motor (Electronic Accelerator, Cruise Control, Idle Speed Control, usually abbreviated EA/CC/ISC). I am unsure of the location of this module, it very well may be what is clicking"

I want to clarify, the cruise control amplifer is what is definitely or was ticking.... seems they have them rebuilt I think. Just wondering if it was just a coincidence that was making noise and has nothing to do with the no start now, but seems to be a big coincidence one day its making noise and the next day it doesn't start, starts and turns off two times while that box is ticking away and then no start and no ticking .......

At this point I kinda hope its that box , as expensive as it is, so the diagnosis doesn't have to go any further, and it seems easy to exchange with four torx screws.

thoughts?

thanks

Replace OVP.

__________________
Zafar
94 E320 58000 Miles

I would also check the throttle actuator EA wire harness. These crumble also and are not part of the engine wire harness.
If there is a short in these wires , they may be feeding back to the cruise module and the clicking noise could be the power Klix-on in the module cutting power from the shorting harness...
????????????

I Agree... or , at least see if it has the new part numbered one...
On 104 HFM, the OVP will cut power to engine management systems [ fuel/ignition/etc ]..

Thanks guys... weirdes thing though I had been assured this car didn't have an ovp when I asked for to be changed last month . yet I got a p/n from fast lane ... go figure... I am crystal on this info given to me which contradicts what I had learned on here. GO FIGURE.

so we are now sure this car did come with an OVP...

Would that be cause for the ticking mentioned b4 in my cruise control amplifier? It would be so easy to just swap this unit if it wasn't $700 ... OMG, wiring harness.... ok.....

Let me go buy a custom made OVP for my car since "they don't bring ovp's in 95"

BOTH opinions are right about OVP's in 1995. And both are wrong!
The E320's DO have an OVP. The E420's (and the other V8's; E500?) do NOT, they have a BM (Base Module) instead. Unsure on the Diesels, probably they do have OVP's, not BM's.

The car DOES NOT have a cruise control amplifier, try to remember that, it has an EA/CC/ISC module, it is not simply a cruise amplifier on this car.
I thought the engine wiring harness which is commonly replaced 9for the fuel injectors) does have the throttle motor harness as part of it but I could certainly be wrong.

Gilly

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Thanks Gilly. Well the source that told me "no ovp for your car" actually saw the car, even opened the hood, :p ... and I haven't changed my badges to read E420, LOL.... Thanks for clarification.

I take it is behind the battery? Just disc batter, remove, and replace ovp? Will there be more than one relay back there to guess which is which?


Ok, EA/CC/ISC.... u do know that part # is labeled c/c/a all over the place including fast lane? If that is the case, then it is slam dunk almost atleast, since it controls so much .

YES definitely the car has no "sole" cruise amp. It is a 95 E320, so it is a HFM 104 engine, which has EA (electronic accelerator). The cruise and idle speed control are all integrated into the EA module, and everything is controlled on the engine by the throttle motor (which has several names; the "actuator", etc). I believe you may see the term "EGAS" on a label on the module.

The OVP on a 124 is usually located behind the black plastic panel which is located behind the battery. You can fairly easily figure out how to pull that panel to access the OVP and any other modules behind there. The OVP is distinguishable by the clear plastic flip-open lid on the top of it, there is a fuse or two under that panel. Very easy to identify. Usually the OVP is help in place by a pair of metal tabs, one of which 9the front one) has a nut and bolt through a hole in the tab. Just LOOSEN the bolt and the whole OVP will slide forward, then you can disconnect the harness plug. Then transfer the nut and bolt to the new OVP and reinstall it.
It is probably worth it to at least try a new OVP, no guarantee here though.

Gilly

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Thanks gilly. I picked one up at lunch. I thought I would have to remove the battery to access it, but it seems that panel is accessible w/o battery removel.

Weird thing is how the ticking cleared up magically yesterday at lunch (remember the clicking only happened 1-2 minutes AFTER turning car off key out or key in don't matter; when you start the car previously it would turn the clicking off.) Like you said I am wondering how it cleared itself, even cruise worked, for a few hours, then got home and nothing... no clicking, no start..

I just am confused , like u said, how it got fixed for a few hrs and then poof. I am wondering if the clicking in the "ea/cc/isc"..... argghh got interupted here and forgot my question, lol....

I am wondering if the clicking and all the led to yesterday (like clicking for an extended period of time overnight, during work, next day 1/2 day also) just burned the thing out....fried it. as expensive as it is I am kinda thinking it might be that... changing the ovp anyway, but can't see how the ovp would drive the radical clicking symptoms

You may want to check the codes from Pin 8 (HFM), Pin 14 (EA/CC/ISC), along with the DM codes.

__________________
Zafar
94 E320 58000 Miles

I have a 1993 300e 2.8 M104. How do you pull the trouble codes and where can I get a list of them? sgtbrent@hotmail.com