From my experience, your car should start and run without the OVP relay. It takes longer to start, but it will start and run. You just won't have power to the Idle Control Valve, ABS Computer, and the Fuel Computer.

But, that doesn't mean you shouldn't have a good OVP Relay. I wouldn't mess with a used one....get yourself a new one.
http://catalog.peachparts.com/ShopByVehicle.epc?q=&yearid=1988%40%401988&makeid=63%40%40MERCEDES+BENZ%40%40X&modelid=6200%3AMBC|1507%3AED|10000013%40%40300E&keyword=relay&subcatid=P:242003@@Overload+Relay&mode=PA

However, it will not run without a good Crankshaft Position Sensor (CPS). If it is going bad, you might have intermittent starting problems or hard to re-start after parking it for 30 minutes or so. If it's dead, then no spark, no start.

Do a search for Crankshaft Position Sensor problems.

Yes , I know it's late on a Saturday night, but I just returned from China and my sleeping pattern is out of whack.

__________________

1993 190E 2.3
2001 SLK230
1971 LS5 (454) Corvette Convertible

Pins are the same and I'll change the 15 to a ten like the other.
Do you recall which pins to bridge for the "get you home" on the FPR socket? It was posted in one of my threads but I'm getting to the age where I better start writing it all down.

I'll also swap out that ECU from the other car since I'm wondering if my taking it out today for a look and rattle may have spelled trouble.

Maybe not, but it will cause a low idle if it is not being operated by the throttle like mentioned in post #3. It was causing my low idle problem 400-500 until I adjusted the throttle so it was closed at start-up.

Closing the micro-switch at 3,000 rpm's caused the engine to saw, just like the manual states and the idle is at 700-750.

__________________

1993 190E 2.3
2001 SLK230
1971 LS5 (454) Corvette Convertible

7 & 8

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1993 190E 2.3
2001 SLK230
1971 LS5 (454) Corvette Convertible

ouch, oh well. I was hoping it might be that easy.

I did my best to search for that part but everything I tried wouldn't show me any "overload relay" (as per the link) at that URL.


I will follow up on reading about it. I'm certainly not qualified to rule it out but I'm almost positive this has to do with whatever we toyed with in the last two days. Or the coil has just decided to quit. I'll know if I see a spark from a plug check right away to look elsewhere. I do have gas - I'm just wondering if I've got all the pressure from that old pump. It's all about dollars unfortunately - I can't just pour a bunch into this car.


I wish I could find a detailed photo of the whole top of the motor showing where all the locations of these switches and sensors are - one of those with arrows pointing to exact locations for old guys like me. I'm ill-equipped with manuals or anything else really.

So would you plant the FPR back in the holes part way to hold the wires down in 7 and 8 or what?

Benzborg, I happen to already have the attached photo of the top of the motor that may help orient you. The micro switch is just out of the frame at the bottom center, approx where the other end of the spring attaches, while the CPS is just out of the frame about center right, down low on the bell housing. The other components shown in the photo are:

B10/8 = coolant temp sensor for the auxiliary fan
B13 = coolant temp sensor for the temp gauge in the instrument cluster
B11/2 = coolant temp sensor for ignition and fuel management
Y1 = electrohydraulic actuator for controlling fuel adaptation under various operating conditions. HTH

__________________
1988 California version 260E (W124)
Anthracite Grey/Palomino
Owned since new and still going strong and smooth
MBCA member

Past Mercedes-Benz:
1986 190E Baby Benz
1967 230 Inherited from mom when she downsized
1959 220S Introduced me to the joys of keepin' 'em goin'

There are only 10 kinds of people in the world--those who understand binary and those who don't

No, with the relay out, put a jumper across pin 7 & 8.

Attached Files

FPR Jumper.pdf (21.8 KB, 224 views)

__________________

1993 190E 2.3
2001 SLK230
1971 LS5 (454) Corvette Convertible

Good pic thanks Cal. No trouble finding the micro switch - is that the CPS down in behind the oil filter - a round looking unit about 2 inch diameter that looks impossible to get to from above?

Long day w/o much luck lads. I have no spark. Lots of gas.
No spark at all from a removed spark plug, held to the block - nothing.
Even held in my hand finally, with care - nothing at all.
Swapped coil and coil wire. My old coil wire works fine in my other car.
Turned into a big waste of time but I don't know any other way to test a coil. Re-checked all my sensors plug-ins and wires carefully.

My meyter shows there is power flowing to the round unit for testing duty cycle at pin numbers 2 and 3 - key in on position reads 3.6V like yesterday. Not sure this tells me anything since I'm sure no diagnostic person.

Swapped FPR, OVP and finally the ECU with battery disconnected. All tne units from the no-start car work fine in the other 300E that starts. None of the units from the working car had any effect on the no-start.

Very much a let down after a lot of work. Will a car start if the voltage regulator is shot? What else could it possibly be ruling out the CPS for the sake of argument. I can look at that last. The "rebuilt" a year ago 70A alternator in the no-start car is suspect - if the answer to my question "will it start if the VR is shot" is no - that's where I'll pick up again tomorrow.


I don't know how to test to see if anything is even getting as far as the coil - thus my swapping it out. The two terminals on top - can I use a meter to see if there's anything making it to the coil from the battery/alternator?

If so how? Keep in mind I'm pretty green on diagnostics.

tia

At the Ignition Control Module, you can pull the CPS off and measure AC voltage while someone cranks the engine. Pull the cable off and read the voltage across the end of the cable while engine is turning over. I think it should be around .9 to 1 volt ac. If there is no voltage, then you will not have spark at the spark plugs.

Also, check the CPS resistance with engine off, (NOT turning over).....it should be between 680 and 1200 ohms.

For record, my CPS pulled off at the ICM reads:

814 ohms and .842 volts ac cold
900 ohms and .986 volts ac hot

Do a search and see what other members have experienced with a bad CPS.

The upper left position is the CPS connection. The other end goes behind the oil filter.

__________________

1993 190E 2.3
2001 SLK230
1971 LS5 (454) Corvette Convertible

You lost me already. I'm even new to using a volt meter properly.
The top left circular hole with that white post in it is where you're pointing I presume? To read the voltage, I would put the red pin of my meter on the cable I pull from that hole and the black pin would then go where?

I'll run these tests but since there's never been any indication of a problem with the CPS I'll have to go at this from where I left off; still trying to find out if a car will start if a voltage regulator is burned out. For the CPS to all of a sudden go when all the related problems have been with the FPR, OVP etc seems improbable. I need to get this car running by morning one way or the other.


I believe I'll have to buy a manual. I've spent much time searching and still would know exactly what the CPS looks like. Is it indeed the round looking unit with a single wire about two inches back of the oil filter on the top of the bell housing? What I'm talking about can even be accessed with my hand since I studied it a bit and couldn't figure out how to remove the wire let alone the cylindrical looking unit. I've read other threads in the forum - here's what they say in general...

"Removing the sensor from the crankcase has been one of my worst jobs soo far. It was kind of bonded in place."

I won't be doing that job.

"You lost me already. I'm even new to using a volt meter properly.
The top left circular hole with that white post in it is where you're pointing I presume? To read the voltage, I would put the red pin of my meter on the cable I pull from that hole and the black pin would then go where?

The other probe would go the the outside ring on the cable....when pushed into the ICM it makes contact with the outer sleeve.

I'm only pointing you to the CPS since you stated there is no spark. A defective CPS can cause no starts, intermittent starts, hard hot starts, etc.

__________________

1993 190E 2.3
2001 SLK230
1971 LS5 (454) Corvette Convertible

Gotcha now. I'm putting the red probe in the center and the black to the outer contact of the plug. In your previous reply you told me to look for a reading of .9 to 1 volt "ac"? How so "ac"?


Oh I totally appreciate the educating. Rather frustrating for a noob like myself. Six hours of no-start after swapping everything possible (except alternators) to rule out this or that wore me out.

Don't rule out the CPS. As slk230 says, the CPS will give you the precise no-spark symptom you're experiencing. That's because the CPS tells the ignition system when to spark for proper fuel ignition. No signal, no spark. That seems particularly likely, in view of the fact that you've already swapped known good ECU and coil with no change in symptoms.

As for the voltage reg, I don't think that plays any role, because it isn't operating until the motor is running. You're starting the motor on battery power, not on alternator/vr power.

EDIT: Sorry, the alphabet soup got me until I just re-read the post. I was thinking EZL when I referred to ECU above. My point there was that the CPS works in tandem with the EZL (ignition control unit), so if CPS and coil are both known good but still no spark, the EZL may be on the fritz. There, I think I'm writing what I'm thinking.

__________________
1988 California version 260E (W124)
Anthracite Grey/Palomino
Owned since new and still going strong and smooth
MBCA member

Past Mercedes-Benz:
1986 190E Baby Benz
1967 230 Inherited from mom when she downsized
1959 220S Introduced me to the joys of keepin' 'em goin'

There are only 10 kinds of people in the world--those who understand binary and those who don't