Unpleasant experience the other day: Drove 45 minutes, turned car off. Few minutes later, car wouldn't restart. Engine cranked fine (so not a battery or starter motor issue), but wouldn't fire. Sounded like it was getting no fuel. Red and green lights on rear view mirror flashed alternately. I ruled out fuel filters, as they were recently replaced and engine has been running smoothly. No fuel leakage issue in lines, connections, or IP.

Quick phone call to dealer's service department. Service advisor said symptoms are consistent with an overheated crankcase position sensor or fuel pump relay. Suggested letting the engine cool, then try again. Sure enough, after about a 20-minute wait, it fired right up.

Questions for the board:
- Does this diagnosis sound right? Any other possibilities?
- Is there a way to test the crankcase position sensor and the fuel pump relay to narrow/confirm the cause before replacing?
- I thought the fuel pump relay was near the battery, under the back seat. If so, how could it overheat?
- How big of a job is replacing the crankcase position sensor?

Additional info, which may or may not be relevant:
- When I got this car about a year ago, it had the surging problem at highway speed. A thorough cleaning of the resonance and intake manifolds and internal flaps seemed to cure it. It came back last week, but I traced the cause this time to a broken wire on the electrical connector atop the EGR valve. That also threw a code P0400 (EGR flow malfunction), which I had cleared after repairing the wire and before the no-start problem.
- The car also had a persistent CEL associated with code P0380 (Glow plug/heater CKT A malfunction). I replaced all 6 GPs but it continued to throw code P0380. Rechecked GP resistance and found #5 to be higher than the others. Replaced #5 with a new plug verified to be same resistance as others; cleared codes. Voila! CEL stayed off. Until the no-start problem the other day.
- When the no-start occurred, the CEL came back on. I was hoping it would show a code related to the crankcase position sensor or fuel pump relay, but no luck. I read it this morning, and it's code P0380 again. (Now I'm not convinced this CEL was generated by the no-start condition. May be coincidence.) We'll see if it stays off this time.
- The engine itself does not overheat. Operating temp is a steady 85-88 C. Coolant recently replaced (Zerex G-5) with thorough system flush.
- ABS and ETS warning lights occasionally stay on for a while after starting/driving. Seems to be a random occurence and does not seem to generate a CEL or OBD code.
- The no-start problem happened again this morning after my 5-minute ride to Autozone to borrow the OBD tester. So it's not a long-distance issue. Again, engine started fine after a 20-min cooldown.

Re: your 2nd PO380 code - You may have inadvertently cranked it on cold GP's during your no start and set that code.

Sounds like the shut off valve may not be opening from your no fuel description. You could confirm that the next time you have a no start by listening for it to open when the key hits pos 2. If was a shut off problem, it could the a bad valve or K40 relay. K40 usually cuts power and cause engine to die while being driven as if key were truned off so i think would be less likely in this instance.

Can't offer much concerning the plausibility of the CPS or fuel pump relay faults other than neither is discussed here much, if ever, on our 606's.

*edit* the CPS is located to the rear of the oil filter canister; you can see it from the top with a flashlight right where the trans connects to the engine. Looks like one hex bolt to remove; access looks difficult.

__________________
Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

Electrical gremlins in my 1996 E300D (W210) . . . .

2.5 months ago, had no-start problem with engine warm (details in first post). Dealer, by phone, suggested overheated crankshaft position sensor or fuel pump relay. Sure enough, car started after a 20-30 min cool down.

Problem went away for two months, but returned this weekend with a vengeance. Now it won't start at all, even cold. Current symptoms (related and possibly not) are:

- No-start condition is always accompanied by flashing red/green lights on rear view mirror. Relocking/unlocking with key fob has no effect. With key in position 2, the flashing lights come on about the same time the GP light goes off.
- Engine cranks fine, so rule out battery, starter. This is more of a fuel cut-off issue.
- No fuel leaks or air bubbles; engine runs fine when it does start.
- Shut off valve on IP clicks when key turned to position 2.
- All fuses (all 3 locations) are fine. Glow plugs are new.
- Engine has never died while running, which is the typical symptom of a K40 relay failure.
- For the last year, there's been an intermittent (and progessively worsening) failure of the speedometer and odometer, accompanied by ABS and ETS lights. Tach and remainder of instrument cluster work fine. Each time speedo/odo decide to start working, ABS and ETS lights go off simultaneously.
- Cruise control quit a few months ago.
- Auxilliary fan now inoperative. Won't start with direct 12v power. Won't start in climate control test mode (both AUTO switches on 10+ seconds). With REST button depressed 5+ seconds, position 20 reading is 10.00 mA (spec), but digital multimeter at fan connector reads 0.00. At same time, I can hear clicking from inside main relay box.

My plan is to start by replacing the CPS ($50-70). I'm not sure what the dealer meant by fuel pump relay, as I understand from an earlier post that this car doesn't have a separate relay for that--the fuel pump function is built into one of the big relays in the main relay box.

Any other advice on the no-start issue?

Any other way to test the aux fan? If not, looks like a new one is in order. Any thoughts about replacing just the motor/fan versus the entire two-fan assembly? I know several members have cautioned against aftermarket assemblies.

Paul

Replaced the crankshaft position sensor today. Didn't fix the no-start problem.

Pulled the K40 relay and popped the guts out for a look. Inside is nice and clean (see pix). Upon inspection with a magnifying glass, all the solder joints but one look fine, and even on that one I can't tell if the ring I see is really a fine circular crack or just a wrinkle in the solder.

Is there any way to test this relay with a digital multimeter? Replacement cost is $125 (dealer) or $102 (Phil).

Do gasser W210's have the same K40 relay? If so, maybe I can borrow one from a working gasser to see if that's my problem. (Diesels are rare around here, but E320's are a dime a dozen.)

Paul
96 E300D

P.S. FYI, replacing the CPS is not complicated, just awkward. It's located just behind the starter solenoid and just in front of the engine-transmission joint, and is visible from above if you shine a flashlight down under or behind the oil filter housing. You'll need a 5 mm hex key socket, U-joint, and about 15 inches of extensions. From under the car, pop the rubber-covered connector off with a screwdriver, then feel for the single hex screw that holds the CPS to the engine. Feed your hex key socket+extension assembly up between the oil filter housing and intake manifold, then fit the hex key socket into the screw head. (Much easier to do this from below than above, but access still requires some contortion.) Go topside, connect your socket wrench, and unscrew. Go back under, remove screw and CPS, insert new CPS and screw. Tighten and replace connector.

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As far as I'm aware, my '96 has no fuel pump relay. There is not an electric pump! I wasn't aware that we even had a CPS, but since you found one, I'll definitely take your word on it.

Look carefully at the solder joints on that board. A strong lamp and magnifier are recommended. You are looking for very fine cracks.

I was successful in soldering mine. You need a high-wattage iron or gun for the "big" connections to the relays and bars. After you solder those, be sure to resolder all of the small relay connections as soldering the big ones will let the relays move a bit, and the small connections will break if you don't reflow them.

Oh, I just noticed that you found one crack. One is enough, if it's in the right place.

If you're good with a soldering gun, give fixing it a try. You have little to lose. The part retails for about $125 at my local dealer.

The red and green lights flashing is telling you the lockout is working and the car is trying to protect itself from theft. If it were mine the first thing I'd do is order a brand new key from the dealer and try that. What you may be experiencing is what I have been through with my '98...failing keys. I have had the two original keys fail to start the car. They both start as intermittent problems. On my '98 the system is a little different though so the failure is not the same but I think the earlier ones would actually allow the car to crank but not start if the car's security system didn't get the right code from the key. If you have a known-good spare key try that too but I know from my experience a brand new key fixed my problems.

While it is possible it is still the K40 that is bad, I'd try the key thing first...then the K40 replacement...I'd bet one will solve it. I don't think the fuel shutoff is at fault because of the flashing lights. There is no electric fuel pump in your car so no FPR exists...but if it did have a FPR it would be on the K40 board...maybe that is why the tech said this.

Both the K40 and key are relatively cheap fixes so you're lucky in that respect.

__________________
Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

When my K40 module failed, I had the alternating lamps on the mirror.

Thanks, Matt L and nhdoc. Both good ideas. But since it's 100 degrees outside this afternoon, I thought I'd try the spare key first.

I have two primary keys on fobs, one spare plain key (black plastic top), and one wallet key (almost no top). Since the two spare keys are supposed to start the car, any "code" the car gets from the key must be based on the grooves cut into the blade. In other words, the fobs on the primary keys are nothing more than infrared transmitters for the locking system.

The primary key blades are well worn compared to the spares, so I had high hopes for nhdoc's suggestion. And it actually worked! Well, sort of.

I tried both primary keys and the big spare. Flashing lights. Then the wallet key. Voila! Engine started.

The primary keys had some crud built up in the grooves, so I thought maybe a good soapy scrubbing might help. After cleaning, I took the 4 keys back to the car. This time, the primary keys and the big spare did not generate flashing lights (I didn't actually try to start the engine), but then the wallet key did! So I tried the primary keys again, and now all 4 don't work.

So I can't draw any conclusions other than this remains an "intermittent" problem.

Cracks in the solder joints of the K40 relay module will definitely result in an intermittent problem. I should have mentioned that my would usually start when it was affected.

Agree'd. K40 fault fails to send signal to open the shutoff valve. No fuel, no start.

When working you'll hear a *click* (with hood up) when the key is turned as the S/O opens.

__________________
Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

Well, I just went out and tried it again, and all 4 keys start the engine. So the key word (pun intended) is definitely "intermittent."

nhdoc might still be right--the primary keys may be on their way out--but I think the next step is to resolder the K40 connections. I'll go find my solder gun and see what wattage rating it has.

If your car has steel keys and not "smart keys" then my suggestion about the keys is probably not right...I thought you had smart (electronic) keys in that car as I do in my '98.

I'd fallback to plan B then and order a K40 relay and try that. It could be that the solder joints are OK but that one of the coils on the relay itself is intermittent. The thing you saw about some of the keys working and some not is probably just the intermittent nature of the failure of the K40 and not related to the keys themselves.

__________________
Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

Found my soldering gun. It's labeled 40/72 watts, 120 VAC. Not super powerful, but good enough to resolder 3 or 4 of the big joints on the K40. (Re-soldering all the joints was too much of a PITA.)

Anyway, flashing red/green lights on the mirror are gone and the engine now starts every time with any key. Of course, this could just be the "good" phase of a continued intermittent problem, but I'm keeping my fingers crossed.

I also replaced the auxilliary fan/motor today. The good news: motor now runs with 12 volts applied directly. (In other words, the old motor was definitely shot.) The bad news: motor doesn't run when connected, either with engine hot and AC at full blast, or with engine off, key in position 2 and climate control Auto buttons pressed for 10+ seconds. Readout #20 shows 10.0 volts, but a voltmeter at the fan connector shows zero. So the climate control module thinks the aux. fan is getting power, but in fact it's not. What's the next step to test?

You put a new motor in? OEM, I hope.

Note that #20 shows 10.0ma control current, but that matters little; that's asking the controller for full demand. This doesn't relate to voltage at the fan plug.

Connect a test lamp to the leads to see if it quickly flashes a few times every five or so seconds. If not, you should check to see if you're getting power to the N65 pulse module, located in the underhood fusebox (you have to remove the cover to see it - six screws). I am not sure where the N65 gets its power. It could be through another contact in the K40 relay module.