Jon, did you also experience this? I'm not sure how you would know a specific relay would click when you're driving the car. Anyway, the air pump is controlled by the RH Motronic ECU, so it's unlikely that this would click on your car. The only thing it has in common with the LH side is "ignition/key power"
Ian, many thanks for the diagrams - what a piece of artwork! I just found the inline plug you referred to - pulled apart and nothing obvious on plug or socket but it does give me some more cables in that area to wiggle with in the morning. I see that pin 8 on that inline has a green wire on it that has a diode (30100) in its path that goes to the slowdown lamp.
Interesting. I wonder what the diode is for. It may be worth checking the diode to see if it is ok. Just wondering if it can affect both lamps.
Having said that, it may be easier said than done: 1) We don't know if the diode is actually attached to pin 8 on plug 41052 (see my earlier comments). 2) Ferrari have a habit of putting diodes in circuit diagrams, but showing the wrong orientation. Anyway, with your diode or resistance checker, put the negative lead on pin 31 of the LH ECU connector (harness side) and probe the pins on 41052 with the positive lead to see if you can get continuity. Then reverse the meter leads. Maybe you can notate which pin that corresponds to on this diagram: Image Unavailable, Please Login
I suppose we shouldn’t overlook the more common problems, such as faulty thermocouple ECUs. I can’t say that I’ve read any official documentation that says that the ECU has to put into memory a fault before turning on the CEL or SDL. The ECU may wait a certain time period before logging a fault. If the wiring checks don’t reveal anything, I would look at the more traditional causes of SDLs, such as failing thermocouple ECUs.
Since it was easy, I had already swapped the thermocouple ECU's over left-right, no change. Need a little more time with the car and a multimeter which I don't have this week. I want to map all the pins from the Motronic plug to the inline plug 41052, the pinouts don't make sense to me and there are no visible numbers on the pins. Will report back again end of next week..
That would be great. We only know one pin at the moment. Pin 11 on 41052 is pin 21 on the LH ECU. Just so we're on the same page, I'll add numbers to the plug: Image Unavailable, Please Login These are the correct numbers for the LH ECU Image Unavailable, Please Login Once we have all the numbers, I can redraw the diagrams. Fortunately, there only seems to be 14 used pins on 41052.
I completed the mapping from 41052 to the left hand ECU plug and I concur that pin 11 on 41052 goes to pin 21 on the LH ECU, at least it does on my car, and there are only 14 used pins on this plug. The graphic is correct on the pin layout Image Unavailable, Please Login Thanks for numbering the pins and they do line up with my mapping. So a few observations : 1. The loose plug with the female pins (not the socket of 41052 mounted on the frame with male pins) has a green rubber seal on it which matches with the graphic on your Fig3 diagram. The Fig2 diagram, which goes to the ECU shows a black plug, which is actually the socket on the frame. I think those plug graphics need to switch diagrams ? Image Unavailable, Please Login 2. I cannot identify the ends of 41052 pins 7 and 8. They do not correspond with the diagrams, I'm guessing that one is to the LH O2 sensor heater and the other is the injector power because pins 17-22 are not used. 3. There are discrepancies also on pins 9-11 (see my map) which go to ECU pins 9, 31 and 21 respectively. 4. Pin 31 from the ECU does go to 41052 pin 10 via Diode 30100. I get a resistance of around 600 Ohms measured one way and open circuit the other. Thats it for tonight. Tomorrow I'll reconnect everything including the battery (disconnected for safety), run a 10 minute 're-learn' idle and do some wiggle testing on the back of 41502. If you want me to map 41051 to the RH ECU I'm happy to oblige if you have doubts about it.
Ah, ok. I didn't realise that the loose plug went to the ECU. Agreed. We just have to find out which is which. Which is easiest to get to? The injector plug or the O2 plug. The heater wires are normally white on the O2 side of the connector. According to some sources, 1k ohms to 10M ohms is good for "forward bias", others say 10's of k ohms to hundreds of k ohms, others say hundreds of ohms to a few K ohms. It sounds rather hit and miss, but I'd say that your diode is ok. That would be great. Thanks! It may take a week or so for me to incorporate the information, though, but I'll let you know when I've finished.
Here's my first diagram (Fig 2) https://www.dropbox.com/t/FVGv42fsD3oGVdjR I've pencilled in some wires for pins 7 and 8 (maybe pin 7 is the O2 heater wire). The first 6 pins/wires were the same as the original, then the wires started changing. Weird.
There will be some wiring differences on the RH bank. The RH ECU doesn't have a tachometer output. Also the RH ECU controls the RH radiator fan. Perhaps you could take a photo of the pin configuration on 41052. Thanks! I'm wondering if the original OEM diagrams were purely for 1994 cars. There may have been a wiring change in 1995. I'll keep a copy of the original OEM diagrams just in case.
Hi Ian, I found the L/H O2 sensor plug, separated the connector and located the two white wires to it. I can confirm Violet/Black (ZN) goes to 41052 Pin 7 as we suspected. Below is a photo and the mapping of the R/H inline plug 41051. It has exactly the same pin configuration and wire entry as 41052. This time Pin 9 goes to the ECU Pin 31 via a Diode with the same 0.6k Ohm measurement as the L/H side did. As you say, there are other differences too. Image Unavailable, Please Login Image Unavailable, Please Login
WOW... thanks for that, Jon. I know how tedious these wire checks can be. I was quite surprised at some of the pin assignments (not what I guessed from pin 5 and on). Here are revised Fig.1 and Fig. 2 diagrams for the 2.7 car (not sure about '94 cars) : https://www.dropbox.com/t/5FnXC5vxkP5whnMg https://www.dropbox.com/t/ylL3UM10lBwWSqsn I've added a note regarding the diode (forward bias resistance) for future reference. Fig. 3 will require some significant rewiring. Standby! Then we can focus on fixing your problem
Jon, did you clean/treat those plug contacts. Some of them look a little corroded. Maybe treat them with some DeoxIT D5 or similar https://www.jaycar.com.au/deoxit-contact-cleaner-rejuvenator-solution-kit/p/NS1436 https://www.ebay.com.au/itm/295253502487?
I hadn't, because I've been reading some negative comment about contact cleaners - not necessarily this one though - and to be honest, I don't know what 'clean' looks like on those tiny pins. I take your comment onboard though. I presume you've used it successfully ? I want to take the car out on a long drive before I do any more, and that won't be for a week. After reassembly and only a short engine run, I couldn't induce the problem now. Its possible the problem was in that intermediate plug and the action of disassembly cleaned up something - probably wishful thinking but hey.. I'll report back either way soon. Many thanks again for the diagrams, they are an enormous help to everyone and I'm just happy to have contributed a little back with the wire mapping info
It's surprising the number of Ferrari defects that have been solved this way. Sometimes expensive parts are thrown at a problem, but all it needed was a plug reset. I don't recall solving any wiring problems by using this product, but if I remember, I do add some DeoxIT to relays and plugs in known problem areas. Thanks again for the pics and data. Sometimes it takes years to find missing information.
Hi, so a short update. Problem still remained on the long test drive (CEL 5-8 short flash, then off, Slow Down 5-8 immediately flickers once). I pulled both ECU's with their respective Cat thermocouple warning controller, cleaned all the connectors and ECU pins with DeoxIT-5 and swapped ECU's over left->right. Ran the car for 10 minutes for an ECU re-learn and the problem is still there on Cyls 5-8. In a way I'm pleased as I think this proves the issue is not internal to the ECU (expensive!). I have not, as yet, swapped the Cat thermocouples over as I didn't want to risk busting one/both of them in case they have welded themselves in. So I may have a highly intermittent Cat thermocouple - that's my next course of investigation. I plan on rigging up a Cat thermocouple bypass on a temporary basis rather than disturb the thermocouples at this point.
Thanks for the update, Jon. Are you going to order a dummy ECU from Technistrada or try one of the DIY methods? 1) putting a 1.5 volt battery across the Thermocouple ECU connector (middle two) pins "Ratarossa style" https://www.ferrarichat.com/forum/posts/147053329/ 2) putting a 1200 ohm/500mW resistor and a 2.5volt/500mW zener in series across the same pins: https://www.ferrarichat.com/forum/threads/simple-2-7-slow-down-ecu-replacement-only-for-no-cats.538719/
I went for option two but used a 2.4v Zener and a 1000 Ohm resistor as that was all I had here. Fashioned up the 4 way plug and proved it worked then went for a drive. Problem still remains - no change in behaviour! No set pattern I can determine but in a 20 minute drive it happened at least a dozen times. Sometimes on perfectly smooth surfaces, sometimes over rough ground, sometimes going onto the gas after a period of coasting, sometimes starting to coast after being on the gas. Since the Thermocouple ECU was disconnected and a fixed voltage was being supplied to the ECU, that rules out the thermocouple and its ECU. I have already swapped over the main ECU's. Reading all the other posts online, I see that the ECU pin 44 (thermocouple ECU input) is weakly biased to +5v, but we are holding it at 2.2V with the bypass resistor and zener, so if there were a brief break or high resistance on that wire from the ECU plug to where I have the bypass installed it would have the same result - the ECU would think it had a momentary high temperature condition. Maybe thats enough to give me my symptoms..
I don't know if the component values would make a difference. If ohms law applies here, there would be 2.083 milliamps using the specified components... and 2.4 milliamps in your setup, but I guess it wouldn't hurt to check the wiring between the thermocouple ECU and the Motronic ECU and to the earths on your heads. Image Unavailable, Please Login Thanks to @F355Bob for the photo. At least you don't have to check the wiring all the way into the cabin (like the 5.2 car)
I haven't been following this thread but it seems that you are trying to figure if you have a wiring problem. May I suggest that you add a jumper wire from the signal pin of the TCU connector to the pin on the 55 pin connect or to which the signal wire goes. Do the same for the ground wire. This will provide a parallel signal path from what ever you connected to the TCU connector (Cat ECU or fake signal generator with Zener) to the main ECU so you won't lose the signal if the wire in the harness is broken and making intermittent contact. If you still get the same flashing SDL and CEL it's not the harness. Hope you understand what I'm saying. Image Unavailable, Please Login
Used an audible continuity tester to buzz out the violet/white wire from the cat ECU plug Pin 'C' to the main ECU pin 44. No tone changes and it measures a consistent 0.2 Ohm throughout a really good agitation of the harness all the way to the ECU. It seems good and solid - I moved and bent the harness and connector ends as much as I dared do. Also checked both ground straps are tight on both heads, with star washers underneath the bolts. Checked again for any stored ECU codes, 4444 (none) shown. Running out of bright ideas now.
Hi John - thanks for the idea and chiming in. I had actually considered moving the Zener/resistor up to the back of the 55 way ECU plug (Pin 44), but didn't particularly want to get into de-shrouding the connector and back-pinning it just yet. I am thinking I need to re-check power and grounds to the ECU though. Which pin, or pins, are the main ECU grounds, my info shows pins 10, 14, 19, 24 and 54 ? Same question for the main +12v to the ECU, which pin 18, 27, 37 ?
