550 intermittent limp mode, ASR error, no RPMs

Hi everyone, I've had my 2001 550 for a little over 2 months, and it has been an incredible dream come true. I've put 5000 miles on the car so far, and admittedly some of them have been "very spirited". However, today it went into limp mode on the highway, and now it takes a few tries to start. Here are the details:

• RPMs drop to zero, but the speedometer continues to work. The engine is operating, but there is no tach signal)
• ASR error light (amber)
• The exhaust sound changes, as if less than 12 cylinders are working correctly
• Now a few hours later, I get the "Slow Down" warning after attempting to start (did the limp mode possibly dump fuel into my cats?)
• When the car does act normally, it happens at random, and then the Check Engine light will come on. Sometimes it will flicker back and forth very quickly, which almost makes me think there is an electrical issue causing this. I thought I could hear a relay clicking, but it could have been my ears. If it was a relay, which one could it possibly be?

Additional details:

• I recently replaced all relays in the fuse box after the wiper/signals/HVAC relay failed (all of them looked very old, and some showing bluing on the contacts).
• The battery has a full charge and shows 12.5v
• I let the ECU reset after a couple hours today, but the issue still persists.
• On two separate occasions the car has been difficult to start, but I thought it was due to bad gas, and a bottle of HEET seemed to fix things. But now I am wondering if those were signs of a deeper issue.

I'd love to hear your thoughts. I plan to take it to my independent mechanic this week, but I'm also anxious to connect any dots I may have missed. Thank you!

 

It is electrical. I would start at the slow down ecu system to trouble shoot.

 

Hate to sound like a broken record, but sounds like a battery issue. 12.5 volts is kind of low.

 

Excuse my innocence, but if there were no tacho indications, wouldn't you suspect the crank sensor (left one)? Wouldn't that also cause the Check Engine light to come on? No crank signal will also cause starting problems. The ASR light, I'm not sure about. That uses speed and throttle information, not tacho.

 

Thanks everyone. The car is showing code P0600 which is a serial error, or can be due to a bad battery. I am aware that the car sat for a while before I bought it, so a new battery goes in tomorrow. Wish me luck.

 

Good luck!

 

The new battery is in, but the issue persists (P0600, no tach, ASR, Slow Down, suspension warning). When the tach does work, there is definitely a relay switching at random, so tomorrow I plan to check them all, one at a time.

Is there a relay that could possibly be cutting power/signal to the tach? Thanks!

 

Tachometer power is the same as speedo, water, oil pressure, water temperature and a bunch of warning lights (seat belt, park brake, etc). You would be losing all of them if it was an instrument power relay. I don't know what a serial error is, and I'm not overly familiar with the engine system logic on the 550, but I'm still putting my money on a crank sensor. One of the crank sensors provides the tachometer signal. Without a signal from this crank sensor, one of the Motronics ECU's may be shutting down some systems (via relays)... fuel, ignition, etc.

Probably time to put your car up in the air and check the wiring on the crank sensors (i.e. check for physical damage and oil contamination). Crank sensor gaps can also be critical. I'll see if I can dig up a picture from the manual.

 

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The crank (or revolution) sensors are the bottom rear of the engine. I've highlighted the one responsible for the tachometer. If you swap over the sensors (and one is faulty), you may still get limp mode, but you may get your tacho back and possibly get rid of a few other warning lights.
I'm not sure if the sensors are shimmed on the 550 (?)

If in doubt, seek expert advice

Sorry to hear it wasn't a battery.

 

Thank you, this is extremely helpful! My car is lowered, so it is completely plausible one is damaged from a close encounter with a speedbump. I'm putting it on my lift tomorrow or Thursday and I'll report back with my findings. Thanks again!

 

Oops... Just found out the left and right crank sensors aren't interchangeable on the 550. Different part numbers.

https://www.ricambiamerica.com/car-diagrams/ferrari/v12/gt-group-2-seat/550-maranello/clutch-controls.html

(Item 2)

Looks like they are on the clutch case rather than the engine, too (but same general area). Left hand side P/N is 164083.

The Bosch part number is 0152186514.

 

I was able to get the car on my lift today, and I checked everything underneath. All looks good and no visible damage to anything. I visually checked each sensor and wire clip, unplugged and re-plugged each one (crank and thermocouplers). Reattached the battery, turned on the inertia switch, disarmed the alarm, and started the car. No RPMs again, but I decided to let it idle for 10 minutes for the security system to relearn. At 10 minutes, RPMs suddenly worked, and the car changed completely. Slow Down, Suspension warning, and Check Engine disappeared. It sounded normal again! But...then things got weird. I still have an ASR light, and I found which relay was clicking when I would lose RPMs. It was ALL OF THEM in the fuse box. So power is being cut to the fuse box momentarily and sporadically.

When I shut off the car and attempt to restart it, it will not start, and just cranks over and over.

Could I be experiencing an immobilizer ECU failure?

 

550s will not turn over when the immobilizer is armed. 575s will turn over, but will not start

 

These sensors also die of old age/heat. Sorry, if I'd thought of it, I would have told you to compare the magnetism and electrical resistance of the left and right sensors. Did you notice that the sensor leads cross over? Keep them that way

If all relays were involved, your engine would stop running. If it's not a faulty sensor, perhaps you're losing power to the RH Motronics ECU (this would stop the tacho working and shut down one bank) or the ECU is failing internally. This may be the cause of the "serial" message. Maybe this indicates data from the RH ECU has been lost.

RH ECU power and right bank sensor power comes from various sources. I'm still sorting out the details. e.g.

Fuse 9 supplies battery power to ECU pin 26 (no relays). I'm not sure how the owner's handbook numbers the fuses, but it should be called "Cylinder bank 1/6 Motronic ECU" (9th fuse from the left?)
The crank sensor is actually powered by the ECU, not by an external power supply.
Pin 27 of the ECU puts out a voltage to the injector control relay (Relay "O"). Loss of ECU power would shut down the injectors, fuel pumps and quite a few sensors on that bank. This is done with relays in the footwell (which is maybe what you're hearing).
Ignition key power obviously has an input into the system, e.g. to the coilpacks, but Left and Right Bank coilpacks get power from a single splice and no relays or fuses are involved.

If you feel comfortable doing so, I would suggest swapping the ECUs to see of the nature of the defect changes. I don't know hard it is to access them in the footwell side panels. Are you familiar with the plugs on them. Be careful not to bend the pins or generate static across them. Check for water ingress around the ECU area (not sure if this is a problem on the 550).

Let me know if you need the wiring diagrams.

Hope it's an easy fix.

Cheers.

 

Thanks for the clarification, I was mistaken. Much appreciated!

Qavion, THANK YOU! You are a genius! My right hand ECU is bad! I was able to swap them tonight, and most errors disappeared, tachometer is back, and only the P0600 code persists, which makes sense. The car also restarts without issues. I then noticed the right exhaust sounds normal while the left exhaust sounds weak and smells of unspent fuel (factory mid-pipe). I am willing to bet if I switch the ECUs back, the exhaust characteristics will reverse. This won't be as cheap as a thermocoupler, but what a relief to make this discovery.

Okay, so my next question is, do I send the ECU in for repair? Or is it likely a simple re-cap job I can do myself? I really hope I don't need to order a new unit. With a quick internet search I found this rebuild service in Florida: https://www.ecudoctors.com/ferrari-550-ecu-0261204186.html

 

P0600 can occur if the hvac system was fubar as you changed relay for it. Based on new weird info I would reset codes with obd2 reader. Check power connection to the fuse box and primary ground. See if you can start car. Then look for new codes to appear. Like if you got misfires codes and feel less power the obd will tell you which holes are misfiring.

Supper important......Have washed the car before this problem started?

 

I've seen picture of the internals of the Motronics units and there are an awful lot of components in those things. The problem could be anything, from a dry solder joint to a fried 100-legged integrated circuit. Even if you spot something that looks toasted, you don't know how far the damage has spread. If "SECU" can fix it for $700, it's probably a safer bet.
Just Google "ferrari motronics ECU internals" and you'll see photos of the internals.

Do you have to send in your immobilizer ECU and car keys with your Motronics unit to these guys? How do they get around the immobiliser chip?

 

Yep, you are not kidding. I ran a search and the internals are far beyond my novice PCB skills. I am calling them tomorrow to ask for more details. Thanks again!

 

Did you check the ECU pins/sockets for corrosion or contamination? I'd hate to see you spend all that money on ECU repair only to find out that the disconnecting and reconnecting of the plugs partially cleaned up the contacts.

It's probably a hassle, but it may pay to try it anyway. Your car may be off the road for a while.

 

Yes, all pins look brand new with no signs of moisture or corrosion anywhere on or near the ECU. I will try the swap today.

 

Sorry, I didn’t mean to ignore your post. I had to think about it and yes, I have seen the slow down error after a washing. It happened only once out of the four times I have washed it, and it was the heaviest of the washes after a 600 mile road trip. The slow down message went away very quickly, so I almost forgot about it. I have read about putting the Cat ECUs in the oven at 200 degrees and then resealing them with silicone while hoping they aren’t already fried. Has a bad Cat ECU ever been known to take out an engine ECU?

Regarding the P0600 code, it always returned after clearing. I tried swapping ECUs back today and the car wouldn’t even start. It seems whatever was still hanging on in the ECU finally kicked the bucket. I sent it off to Specialized ECU Repair today along with my immobilizer boxes and key fob. I have it in as a rush job, so hopefully I can report back soon.

 

Specialized ECU Repair found the issues today. My right ECU’s power supply went bad along with some of the transistors. They are repairing it now, and I will report back when I have it in the car.

 

ECUs arrived this morning and I just drove 20 miles. It drives like a dream! Thank you Specialized ECU Repair!

 

Wow, that was fast... and during a hurricane. Great to hear.

Do you have an informal digital logbook/diary in which you can record maintenance and search through quickly? Some folks forget things like how old their battery is, etc). I got about 10 years out of a refurbished ECU for my Lotus (which only cost me a few hundred dollars).

Did you buy the car relatively cheaply? Call me a cynic, but I'm just wondering if the previous owner knew about the problem and, not realising the repair was relativly inexpensive (albeit with quite a bit of DIY diagnosis), sold the car as fast as he could.

 

The logbook is a great idea, I will do that. I purchased the car from a well known and respected Ferrari dealership, and the issue took a few thousand miles to manifest itself for me, which makes me think I was just unlucky with aging electronics. But it was a consignment car that had been sitting for a while, so who knows. It passed its PPI with flying colors from another well known and reputable shop, but given how intermittent the problem began, it’s possible none of us noticed it until the day the car went into full limp mode. I asked Specialized ECU Repair if this is normal for these cars at this age, and I’ll report back with their answer.