456 M GTA, OBDII code - P600 , ASR & Transmission light on

Just a quick post to enable other 456 owners to try and resolve issues that they may think are terminal....

History:

My 456M GTA had an issue where the gear box stayed in limp home mode - no warnings nor indication lights - just violent gear selection fron N to D and from N to R, only 2nd gear available (to check drive the car in D take your foot of the accelerator, revs drop right off, no engine to gearbox link - select 2, and you will feel the engine braking and decelerating the car).

Occasionaly on a drive (when i thought sod it....its only the same as leaving it in 2nd gear anyway) the slow down light would pop up..slow down and then it would disapear, as engine working hard..accepted this as a normal warning.

No amount of trawling the net came with any useful info.

After leaving the car for a two weeks whilst on holiday, i returned and turned the key in the car, shifted from N to D, all smooth and sorted...no idea why just resolved itself.

Then the imobiliser on the vehicle would not turn itself off, and the gear lever lock solenoid would not disengage......new battery....all resolved.

Then two days later the car decided after a 90 mile run and a stop of less than 10 minutes to display the ASR warning light, this cut the power and shut down 6 cylinders + limp home gear box mode.

Tried days of disconnect battery (terminals not cut off switch ) recharge battery, idle for 5 mins on restart...nothing reset it.

Then on one out of the blue day, started fine, no issues, drove for 20 miles, stopped for fuel, restarted....ASR and 6 cyliner + limp home mode with the gearbox safeguard.

After checking all electrical connections, WD40, reseating all ECU multi plugs etc....no change.

Then discovered that part of my symptoms were similar to the cat ECU thermocouple issue.

After reading numerous threads on what they actually did - ie monitor cat temp, very little else.

Took the plunge and disconnected both ECU's. disconnected the battery for half an hour, then restarted the car, air con off all electricla loads at a minimum, did not touch the accelerator, half bank issue still there, but now with ASR and slow down lights on dash. I had read a post about leaving the engine cycle for two coolomg fan cycles...so let it run.

Two fan cycles and no change in running.....switched off the ignition and left the car sit for 20 minutes.

Restarted the car -but left the key in position II for a few seconds, no more that 15, watched the check lights cycle and no warning shown....turned the key and all 12 cylinders now in operation...then shifted the car from N to D - smooth surge, then from D to N to R, smooth surge.

So far 60 miles and 5 engine starts and no warning lights (other than the slow down warning due to non signal from cat ECU). Only have one slow down light does not inicate a bank issue so, i will replace both cat ECU's at some stage.

I have no idea if this is coincidence, but knowing the electrical "wonders" of the 456 - all of these problems could have come from a malfunctioing cat ECU.

So in summary if you get an ASR or reduced power or limp home gear box mode warning...before trying all electrical connections and spending weeks trawling the net and finding only four other instances of your scenario that have never been posted with a resolution and thinking your prancing horse needs to be put down.

Try :

Disconnect battery
Leave for 15 mins
Reconnect Battery
Turn key in position II for 20 seconds
Turn off ALL electrical items in the car AC etc
Start the car and let idle for two or more engine fan cycles
Turn off the car and let stand for a few minutes
Restart and check if all has re set.

If not -

Disconnect BOTH cat ECU's
Repeat above

If this has not reset your problems, i am afraid i have now become post 5 about an issue you are experiencing, that has no resolution.

I wanted to share the experiences and issues, and the tests and solutions that worked for me, to hopefully help any body else that may have been affected by the smae or similar issues and provide a step guide of something that has worked....rather than feel there is no way out other than the dealership or independant.

I hope this helps at least one owner resolve an issue...that did feel like the end of their ferrari ownership.

Apologies for the war and peace post - but when i was looking for answers or similar scenarios there were numerous posts on what could help, but no replies as to success or any step guide on avenues to explore.

Thank you for reading!

 

I was very interested in a 456 GTA UNTIL Iheard from several folks including a doctor friened of mine here in Atlanta the the "automatics" had some real issues early on and I was advised by 3 differnt folks to ONLY buy a manual; while I do not have an answer I am assuming that this may NOT be electrical but a true tranny problem, good luck, and I hope NOT! dog

 

Try the battery reset and ecu swap / disconnect - it took me 6 months of tranny shop, electrical "experts" to trace that this was a battery and or coincidence sequence of events....just hope you dont experience the solenoid on the gearstick becoming stuck in the lock position so you cant even drive the 456...

 

So love the car but mine has electrical issues it ate the alternator 2 years ago. Now the transmission warning light comes on and off, so we changed the fluid filter etc. and it checks out fine shifts fine but the light still comes on and off. Now the slow down light has started flashing for no reason of course right after I turned the headlights on. My question is has anyone replaced the ECU in one of these and did fix the problem or dose it just need rewired?

 

Just a little update on your post so others can see... I guess you have fixed your CR by now, but I write this anyways!

If the Slow Down light comes on, the only way it can come on is if the exhaust is too hot. If you have fuel, but not perfect spark, then it will come on immediately. My car once had a bad connection in the connector at the underside of one of the coil package. Both engine ECUs working like they should but because the car misfired and sometimes ran on the other cylinder bank, the light came on and sometimes flashed. This was my 550 with a manual gearbox. Put some WD40 in the plug, and the car runs perfect. I had another car some years ago, which was a Maserati quattroporte with four double carburators. When i bought that car, only three of the four carbs got fuel. Intake float valve stuck in closed position. So then the car only have 3/4 power, the Torqflite auto box «feels» that the engine is not pushing while the throttle link from the throttle body to the gearbox give a different signal. Then the car needed to get higher up in revs to shift to next gear and it shifted quite hard. When I fixed the carburtor, and all eight cylinders again ran like they should, the gearbox shifted smooth as butter!

So If your engine doesn’t run perfectly, I believe it can affect the gearbox too. And your more modern gearbox mitt be a little «confused» and send the transmission problem warning light.

 

Erik-A bad thermocouple will also give you a slow down lamp with no other problems.

 

Intermittently this would be happening to me as well. ASR and Tranny light (box with stick) light will come on and then limp mode. After letting it rest and sit, restart and runs perfectly fine. It sounds like I'm the sixth person that is happening. I've tried searching and found no resolution, has anybody been able to determine/find out more what the root cause is?

Everything else is fine. The car runs well otherwise.

One super odd thing is when I plug in my ODBII tool, the light will come on during startup, unplug it - no issues. Weird.

Had it checked out by Ferrari Silicon Valley, they were scratching their heads....

Thanks in advance to the community on anything new that has been determined.

 

I don't have any notes on the auto gearbox. Is there any data shared between the transmission control unit/s and
1) the engine ECUs or
2) the ABS/ASR ECU?

The ABS/ASR ECU, of course, has to output data to the engine ECUs for power limiting. The ABS/ASR box also provides vehicle speed to the whole car, but I would expect the engine ECU to show a fault code for loss of speed data (and, of course, the speedo would stop working). Similarly, if the Right Engine ECU lost crank sensor information (engine rpms) and couldn't provide data to the other computers and tachometer, you would expect associated fault messages.

The problem may be related to temperature (as the problem goes away after letting the car rest and sit), but temperature can affect almost everything... sensors, ECU internal components and wiring. I've even seen grounds affected by temperature.

Do you mean you're plugging your OBD2 reader into your engine ECUs?

 

Good question, I getting my actuators rebuilt, which may cause some cross-interference, just my own conjecture.

I appreciate the ideas, keep em coming. I've checked the Cat ECUs, replaced all 4 O2 sensors, have 2 new engine ECUs. I figure what I'll do is clean up other modules and units as well. Thankfully, the car runs excellent otherwise, so I'm pretty sure it's just a minor gremlin.

When I plug in my OBD2 reader into the port (and do nothing else) - the ASR/Transmission symbol shows up during startup. Simply unplugging the OBD2 reader makes both go away. Crazy huh?

Thanks again @Qavion for taking the time to respond and providing your thoughts, I always appreciate it.

 

So the past 100 miles have been trouble free, and I found this thread that described the same issue I had.
https://www.ferrarichat.com/forum/threads/456m-gta-stuck-in-second-gear-beware-of-obd-ii-tester.299191/

in a nutshell, some OBDII readers will make the transmission light and ASR light come on (and put into limp mode) just by being plugged in, so be careful of that.

 

I had similar symptoms when my alternator went bad. After changing a new alt and reset by unplugging/plugging TC ECU it fixed the problem. Make sure voltage is good.


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