Hey Guys, Car has been running fine. Took it out recently, no problems. The other day I was just moving it around the garage and the slow down light was blinking. I thought maybe it just hadn't warmed up, but no, it keeps going. I've read all the threads on this issue-so I did do a search. My mechanic is a bit backed up, so I can't bring it to my professional for now. The fact that the light blinks on immediately after start up pretty much points to a diagnostic problem rather than a real problem with over heating cats etc. The car has stock everything (97 Spider). After carefully reading the threads, I learned a lot. One thing I learned is that an easy way to find the ECUs on each side of the car is to follow a braided steel line up from each cat. Using this information, I located both ECUs, I think!, and they are both in spots that are difficult to photograph but in the interest of future FChat people trying to do this, I thought I would provide a picture. The picture is bad, but it's really bad for another reason, it does NOT show the braided steel line that IS running into the top of this brass colored box. So there are two connections into this box, a steel braided cable that comes off the cat, and this connection you can see. Both connections are mounted on the face of this brass colored box. My understanding from reading the previous posts was that if I disconnected the connection you can see in this photo, from both the right and left ECUs, the blinking slow down light should stop. That is not the case. I've tried disconnecting both, and cycling the battery quick disconnect off and on, and still I get a blinking slow down light. Maybe this is not the connection I am supposed to disconnect? I also looked carefully at the connectors going into each ECU as other posters had mentioned them cracking and needing silicon. But mine look really good. In fact all the connections, the steel braided cable connections, and the connectors in the photo all look good. Would appreciate any thoughts. Image Unavailable, Please Login
Visual inspection is not a sure fire way to tell if there is a problem. I had a bad one, and it looked fine. Good you have the green ones, those are the updated ones, used on the 360, which are more reliable...but still can fail, as all mine are green, and still one went bad. Not definitive, but usually the problem is with the cat ECU, rather than the thermo probe. You have three cat ECU, left, right and center. Only the left and right will trip the "slow down" light. A failure of the center cat ECU will trip a "Check Engine" light. So best way to figure this out, is by swapping the right side cat ECU with the center cat ECU. Start with that, for two reasons: one, I was told once the right side fails more often (not sure why that would be) and because they are next to each other, which makes the swap easier. You do not even need to physically move them. Simply disconnect the thermo probe and electrical connector from the right, and plug into the center. Take the center ECU probe and connector and plug in the right. You can figure out which is which by tracing the probes, like you did earlier. See if the problem switches from a "slow down" light to a "check engine" light. Since the "slow down" light comes on immediately, this should give you an indication immediately upon start up. If the light goes out, you found the bad one. Leave it in that position (center) and it will probably throw a CE light in a few days, weeks or in my case it took a couple months. Good luck and report back.
Firstly, I really appreciate the response, and the clear directions. Didn't realize there were three of these connections. At first I misread your instructions and JUST switched the electrical connections on the center and right ECUs. That did not change anything. Still got the Slow Down blinking light. Then I came back and read more carefully and realized I was to switch the probe connections as well. So then I changed both the electrical connectors and the probe connectors between the right and center ECUs. But this did not change anything, still getting blinking light. Earlier today, I had disconnected the electrical connectors only from first the left and then the center ECUs. As I said before, that did not change anything. In the interest of being consistent, I just disconnected the electrical connection to the right ECU and that did not change anything. Finally, I disconnected all three of the electrical connections from the three ECUs, but still the blinking slow down light. So...this is confusing. From reading previous threads, it seemed like disconnecting one of these ECUs should have stopped the blinking, even if it meant the car would record some faults. Doesn't make sense to me.
Disconnecting the cat ecu's on a 5.2 car will cause the slow down light to flash, not turn it off. Personally I would scan the car and see what code it is throwing then swap components and see what the problem follows (ecu or thermocouple, sounds like ecu is most likely)
Short of having two bad cat ECU's. I would return the wiring back the way it was. Then physically swap the center and left catalyst ECU's.
I never got a "check engine" light or p-code stored with my "slow down" light...but worth scanning, just the same...might even be a pending code stored...you never know.
I'll have a look tomorrow. Getting late here. The left ECU looks pretty easy to get out. But the center and right look a bit more difficult. With some good lighting it might not be too bad. I don't have a way to read the any codes, so that will have to wait until my mechanic frees up some time. I'll report back. Really appreciate the suggestions.
Hi Guys, My mechanic is still pretty busy, so I did what the pros here hate, and I ordered a replacement ECU from Rutlands. It was a used unit that they said was fine. A couple things: Note but probably irrelevant. This new unit IS green. All my older units are a metallic yellowish color. My poor picture earlier in the thread may have confused things. I took the "new" ECU and replaced first left, then center, then right existing ECUs. But in every case, the slow down light keeps blinking. So...not sure where to go from here. Probably to my mechanic. I didn't think it would matter but: 1. In swapping out the ECUs I did not actually remove them from their mounting spot. I just removed their connections and plugged these connections into the "new" unit. 2. I didn't cycle the battery on and off during any of this. 3. I only left the car running for half a minute during each of these tests. I figured that when things were working, before this problem, the slow down light goes out immediately, so if everything is back to normal, that should happen now too.
Could be more than one bad ECU. Also, can you be certain your new one is good? And have you checked your thermocouples to ensure they are okay as well?
Yeah. I obviously knew I was taking a risk buying a used item. But figured that Rutlands, which is a reputable group, said it was good, so it was a pretty safe bet. And not that expensive. All your points are possibilities. I would think the possibility of TWO ECUs failing within a week would be pretty remote. Meaning that everything was fine, and then I got the slow down light and it's only been 10 days or so of trying to figure this out. So I think your idea of some other element within the system is a better possibility. I'll be in touch. Really appreciate the feedback though.
Or another twist to the plot. You could have good ecu's and a bad thermocouple/s, or one of each that is bad? OR........they all could be good and you have a wiring problem? The difficulty you are having in hunting this down is, your car is a 5.2. You only have one slow down light to work with. The 2.7 cars have one for each bank so that makes it a bit easier to track down the problem. f355spider posted a GREAT way to check for your slow down light problem. So the thing you are going to have to do is take your time and be methodical about it.
Hey Guys, Wanted to update you. My mechanic is still pretty busy, so the last couple days I have been reading a bit more on other people here, who have had the same slow down blinking light problem. I came across a thread where one person said he had to wait about 15 minutes for the slow down light to go away after replacing a particular ECU. So...I turned the battery to the off position using the rotating knob. Replaced the ECU that is the "middle ECU", just by plugging the two wire plugs into the new ECU. There are two ECUs in the rear right corner of the car. This one was the one closer to the car center. I turned the battery back to on. Started the car, and let it run for 15 minutes or so, keeping a pretty good eye on it, in case there really was some problem with cat temps. I was shocked to find, when I returned to check on the idling car, that the slow down light had gone out. Shut down the car, and restarted, and it seems like it is gone. I will now remove the presumably non-functional ECU and bolt the "new" one into the position. So...it seems like you guys have saved me probably at least a full day of my life. And probably hundreds of dollars! My mechanic is 1.5 hours away. I would have to get someone to drive me back and forth, twice. Probably during business hours. And then there would be the repair costs. Meanwhile, I've spent some good quality time with the car. And learned a lot. Excellent. Thanks for your thoughts. Hopefully it will stay good. I'm going to resist really driving the car until I get the replacment ECU bolted in place. One final thought. For sure the blinking light did not go off immediately after replacement of the ecu. The fact that it took some minutes makes me think that a lot of the swapping around I did before was not really useful because I didn't allow the car to run for a while, and learn that everything was okay. Also, probably not that important to cycle the battery on and off. Even after turning the battery off, the car started up with the light blinking. So it remembers where it was. Only after it had some time with the new ECU did it sort it self out.
BTW, I did learn that the left and right cat ECU's CAN throw a "check engine" light along with the "slow down" light. I never got one, though mine was intermittent in nature, the light would only come on every once in a while for 20 seconds or so. A friend had his on almost constantly and it definitely set fault codes with a CE light.
Funny how these things work out, but I have been reading along with this thread (as I tend to do, always gathering 355 info for the day it'll be useful), and yesterday my slow down light started blinking. No power loss, car running fine, as it has been for some time now. (BTW, sorted '98 355F1, 26,xxx miles, bought it 3 1/2 years ago with 13,xxx miles on it.) So, as I am about to embark on my trouble-shooting of this problem, I will be following the advice given here. I did call my shop, and basically had a re-run discussion of this thread, with the same trouble-shooting advice given to me. My car's doctor also added that the newer green ecu's not only are better sealed against moisture, but they are programmed with looser tolerances of exhaust temps, so are less finicky as far as desired range of operation. He echoes the sentiment that 9 out of 10 times the SDL is due to the ecu, and that 9 out of 10 times the newer green ecu's don't fail. My problem is I have 3 older-style ecu's. So, this may be a recurring theme for me for awhile... Still, I love that crazy car! Thanks all of you for posting these problems and their (often simple) solutions. Makes life easier and less mysterious for the rest of us. Hopefully I can one day post an actual novel idea and help out the next guy. (Except that would mean I have 355 trouble, which I don't want...) John
John, the simple solution to eliminate headaches might be to replace all three and be done with it. The previous owner of my car did that...and until a couple years ago, the "green ones" were doing great, until one finally got finicky.
Well, today I swapped the right and center ecu's, and still the SDL flashed. Based on the logic presented here, I figured that the left ecu must be the bad one, assuming the thermocouples were good (almost always is the case, per my tech). So, I thought it worth the gamble to replace the left ecu with a new green ecu. Ferrari of OC is only 15 minutes away, and they had one (only one!) in stock. Being that I realistically expect all 3 of my old ecu's to fail sometime in the near future, I figured "why not?" and bought the ecu today. I put it in the left position, reset the battery, idled the car for 15 minutes, and sweat bullets! Because, the SDL was still flashing during the 15 min re-learn period, and then as I drove off to road test the car, still flashing for first minute or so. But, after a minute, dash light went out, not to return. All is well again. Of course, the other 2 ecu's will still fail inevitably, but I placed an order with Daniel for 2 more green ones. I'll swap them out at my leisure when they arrive, but glad I went to the dealer today as it gets me back on the road NOW. I called my tech to thank him for giving me phone advice (and hand-holding), and I want to thank you all as well for providing me with guidance as I encounter these speedbumps of 355 ownership. John PS: Daniel's price for the ecu's was $30 cheaper per unit than the dealer's price. And, no tax plus free (standard) shipping makes this a cheaper route to go for any of you doing this as a preventative measure or are willing to wait a few days for the parts.
If you own a F355 and have any miles on it you have replaced the ECU Converter Catalytic Processor (Ferrari part #000179278, available thru Ricambi America http://www.ricambiamerica.com/ or Forza Ferrari) that initiates the Slow Down light(s). If you have a higher mileage car like mine (45K) you have replaced them or at least one more than once. With 45K on my 355 (early 1997 with 5.2 Motronic ECU) I was facing another trip to my local Ferrari Dealer to find out which unit has failed (again). Because it is a part of the emission control system/process, they quoted me a bit over $500 to do the diagnostics. Well I have found an alternative (note early cars with 2.7 Motronic have two slow down lights so diagnosing is easy, not so with 5.2 only one light and it covers three Converter ECUs, RH, LH and exhaust Bypass). Nicks Forza Ferrari (http://www.NicksForzaFerrari.com) has available to non Ferrari shops and anybody with money the expensive but extremely versatile Leonardo analysis tool out of Italy. This tool covers MANY more cars than Ferrari, but for sure all Ferrari models. Nick did a test/demo on my car and it was incredible. Note; I am a competent Italian car mechanic having built several Alfa fours and sixes and two Dino V-6, 2.0 and 2.4 and do all the service and repair on my 355, except engine out services. With that said, if you have a problem with the Slow Down indicator on the 5.2 Motronic Vehicle, it MUST be analyzed. The option is to spend $329 times three and hope that will solve your problem. So find a shop that can do the proper analysis and if they have a Leonardo Analyzer the entire cars electronics can be done in less than a half hour, that is EVERYTHING, suspension, engine, brakes, convertible top electronics, et al. Now if I could find a shop in the greater Seattle Area, other than the local dealer that would be great.
Hi Clyde!' Long time no see! Please PM me via the email system here so we can exchange email addresses. BTW, if you get a "Slow Down" light, it has to be either the left or right side cat ECU. Simplest to just buy one, and swap it on the right or left side, and if the light does not go out, try the opposite side. The center cat ECU will not trip a "slow down" light, only a "check engine" light. The diagnosis on these systems does not require an SD1/SD2 or Leonardo...but definitely can make it faster and more definitive process if access to one is available.
