CEL but no DTC

Apologies if this was discussed already but I searched through older posts with no luck.

For some time on my 2000 550 the amber "Check engine" light comes either when turning the ignition on before starting the engine, or when cutting off the engine. The light turns off right away after the engine has started and comes on for a few seconds after cutting off the engine. It seems this light is controlled by a relay as I hear a click in the passenger footwell when the light turns off a few seconds after cutting off the engine.
The engine runs as good as can be with no displayed error, but my understanding is that some issue was recorded at some point and was stored in the ECU(s?).
I recently invested in an OBD reader with the suitable Fiat 3-pin adapter and I am puzzled that the reader finds no DTC or Pd DTC code stored in either ECU.
Things likes IAT, ECT, TPS, STFT and LTFT are where they should be.
Where should I be looking at?

 

Sounds normal.

The RH ECU provides both power and an earth for the light. Power is supplied via relay "O" in the footwell. The RH ECU energises the relay.

The light appearing with the ignition on (engine off) is just to let the driver know that the light is working.

 

The service manager at Ferrari of Houston told me to put black tape over the CEL.

 

The dodgy previous owner of my F355 wired up the light to come on during start, but not if there was a fault He didn't tell me about the other 30 issues, either.

 

Apparently, the problem is Ferrari didn't understand how to place sensors. If you drove over a little puddle of mouse pee, it would trip a CEL.

 

...and imagine what the "mouse pee" is like where I live...

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That's funny. My old Shark used to hate deer. I can't imagine the reaction to Roos.

 

Thanks.
After turning on the ignition and letting the system perform all checks, waiting for the "CHECK OK" on the main display to turn off, two lights stay on until starting the engine : the amber "Check Engine" light as mentioned, and the battery light. I can understand that the battery light stays on as the engine is not running, but I would think that the "Check engine" light should come off if neither ECUs have stored any DTC code, especially if that very light turns on again for a few seconds when turning off the engine.
I do not remember the CEL to stay on within the described pattern when I purchased the car, and I cannot remember for sure but I think this pattern started after adjusting the throttle bodies and the TPS. The engine runs very well, better after adjusting the throttle bodies and TPS, with no issue that I can observe.

 

I guess you'd have to ask a fellow 550 owner, but that's the way it behaves on my 5.2 F355. No light out until engine started.

 

Ok, but does the light also turn on for a few seconds when you turn off the engine?

 

On 575s, the CEL lamp is lit until you start the engine. Not sure about shut down, since I never really paid any attention to that.

 

Interesting.... I just started up my F355 and ran it for 30 seconds to see what would happen. There was a delay on startup, but the light extinguished straight away after turnoff. But if I just turn on my ignition and off again without starting the engine, the CEL takes about 3 seconds to extinguish. I don't know if the light would have taken longer to extinguish if I had kept the engine running for longer. I knew there was some kind of delay as when I am working on my car, I always hear relays clicking off a few seconds after I turn off the ignition.

It would be interesting to see what happens on a 550. I don't have an OBD port on my car, so it's a bit of a hassle interrogating my Motronic ECU to see if I have hidden issues. The car runs normally.

 

@Qavion
Thanks Ian. To be honest perhaps I have been making this up and my 550 may have been doing that since new. However I miserably fail to understand the logic behind turning the CEL on for a few seconds after switching the engine off. Perhaps there just isn't any logic at all in the end?
As you said, if a fellow 550 owner could check this out on their car this would be most helpful. Thanks in advance.

 

Must be just the 550. When I shut off the ignition on my 575M today, all the lamps extinguished immediately. May be some differences between 5.2 and 7.1.1 at shutdown.

 

I thank you Mr. Phillips for checking this out. It is of no surprise to me that the 575 ditched some of the puzzling gimmicks of the 550.

 

Make sure your OBD reader is compatible with the Ferrari's ECU.
Check the relays and connections in the passenger footwell where you hear the click.
Look over the battery and ground connections for wear or corrosion.
Maybe get the ECU checked out by a pro. If nothing shows up, you might need a more advanced diagnostic tool or have a technician with specific experience in that area take a look.
Hope that helps.

 

^^^^^^
Newbie alert

7 posts in one hour offering generic/obvious automotive advice on multiple FChat forums.

1) The ECU is controlling the delay on relay "O", so there is nothing wrong with the relay itself. Nothing else but the ECU would control the delay on this relay (which controls the CEL bulb power)
2) The battery and ground connections have nothing to do with this. The ECU is initiating the delay. A low battery should generate a low voltage code. A $10 cigarette lighter voltmeter will tell you what your battery is doing.
3) Proper Ferrari diagnostic tools are well above the average 550 owner's budget. e.g. $10,000 for second hand SD1/2 tools.
4) A fellow owner's (or two) comment on common behaviour is a lot more comforting that telling him to seek expert advice when it may not be needed.

 

Things are getting clearer... or not.

Despite registering no CEL I did perform a clear code function with the OBD scanner which seemed to have brought results. Not only did the engine ran smoother than ever aftwards but the CEL light did not turn on again after switching off the engine... up until after 2 hours of driving when not only the CEL light came on whilst driving but also the CHECK ENGINE label in the multi function display, with no impact on performance thankfully as the engine never ran as smoothly since buying the car.
This time however the OBD scanner returned one DTC: P0123, for TPS calibration, which was at 11% with the engine not running, It seemed I was correct when I said that the CEL coming on for a few seconds after turning off the engine started after indexing the TPSs.
After setting the TPS value back to 0% and clearing the DTC the CEL turns off when starting up the engine but I ran out of time to go out for a drive.

I still do not really understand the logic behind what I am going through. Why did clearing DTCs in the first time - despite not seeing any - later got to trigger a proper full on CEL on both the amber light and the multi function display with the engine running, for an issue that I had caused but that did not register clearly before clearing DTCs?

 

Interesting.

If you don't start the engine, do you get a 2~3 second delay on the light if you turn the ignition on and off?

Yes, very strange. It's a good faultfinding tip, though.

 

After clearing the DTC I only had time to start the engine and let it run for a few seconds, but things seem back to normal :
- the amber CEL turns on with the ignition then turns off when starting the engine
- the amber CEL does not turn on anymore when turning the engine off
- no more CHECK ENGINE label on the multi function display.

I will get back with more observations after the next drive.

 

I drove the car several times since clearing the DTC and no new DTC has registered since. The amber "check engine" light turns on only after switching on the ignition and turns off when starting the engine, and does not turn on anymore after switching the engine off. No more "CHECK ENGINE" label on the multifunction display. It seems both ECUs are happy now and are not seeing anything wrong in the system.

One thing I really don't like about this Bosch engine management is the relearn process. I find slightly irritating that idle speed never seems to be adjusted correctly even after respecting to the letter the 10 min at idle rule and driving the car afterwards in all conditions. Sometimes the engine would keep idling at 1400 rpm, then I would turn it off, turn it on again to see it idle at the correct 1100 rpm, then after driving the car again for a while and it would idle back again at 1400 rpm. Sometimes it would settle at the correct 1100 rpm but some other times it would not and there is zero logic behind it. This is a total PITA, as this erratic idle is exactly the reason why the fuel cut when closing the throttle affects how engine speed collapses and dictates how easily or not 2nd gear will engage.