| Author | Message | ||
| James J. McGee (Dr_ferrari)
Junior Member Username: Dr_ferrari Post Number: 56 Registered: 7-2002 |
Paul, If you order the pn#156669, you should get the correct relay. even if you order the old number, it will be updated to the newer type if ordered from a Ferrari dealer. Regards, Jim | ||
| John Kelly (Jaykayuk)
New member Username: Jaykayuk Post Number: 19 Registered: 4-2001 |
Excellent, Another inexpensive fix on a Ferrari. I wonder what they charge for the official relay ? Its great that we can all help each other in this way. I am beginning to get a little less nervous about the cost of fixing these cars as I hope to get mine later this year. | ||
| James J. McGee (Dr_ferrari)
Junior Member Username: Dr_ferrari Post Number: 52 Registered: 7-2002 |
Paul, If your looking at the 348 spider parts book it should be the new type. I will check my notes at the shop tomorrow and let you know the correct part number. Best regards, Jim | ||
| Paul Hill (348paul)
Junior Member Username: 348paul Post Number: 91 Registered: 12-2002 |
Actually the parts manual has 156669 (Tav145-51) listed for the relay - its the only one - seems promising! Paul | ||
| Paul Hill (348paul)
Junior Member Username: 348paul Post Number: 90 Registered: 12-2002 |
One thing that I also forgot to mention is that if a relay is sourced from elsewhere, it only needs to be the 4 pin type- There is no connection in the fuse box for the 5th (middle) pin (The original relays have 2 "87" connections - the middle pin is just another "87") James, Do you know or know how to find the part number for the "Gold" Relay? Thanks Paul | ||
| James J. McGee (Dr_ferrari)
Junior Member Username: Dr_ferrari Post Number: 51 Registered: 7-2002 |
Paul, Again, you got it right, the diode was incorporated in the newer gold relay. all cars were to have been updated before they were delivered but one or two must have slipped through. the diode prevents the voltage feedback through the relay (condenser fan) control feed wire from the ecu. If the ecu recieves a voltage spike, it will shutdown and possibly give an "E8" error. Regards, Jim | ||
| Paul Hill (348paul)
Junior Member Username: 348paul Post Number: 88 Registered: 12-2002 |
James, I am certain that there is no feedback to the ECU from the Tri switch. The green/black directly switches the 12v+ to the clutch (Lo & Hi pressure) and the blue/white (medium pressure) switches the 12V to the relay coil for the condenser fan. (There is a clutch relay that is before the Tri Switch as well) If the system were over pressuring, the Hi switch would go open circuit therefore de- energizing the clutch � but you would still have 12V from the ECU on the Green lead The diagnosis I made was to disconnect the plug at the Tri switch, disconnect the lead to the condenser fan so that only the relay would work, then turn on the A/C without the car running � You then have the 12V+ coming up the green wire into the tri switch socket - Just by putting a jumper lead between the Green & Blue/white (ECU 12V+ and Condenser fan relay) would energise the condensor relay, and then releasing it would cause the 12v from the ECU to drop (Back EMF). I believe there is an over voltage protection in the ECU unit, hence when you turn off the A/C then back on the 12V was restored. As a double check, I took the relay out of the fuse box & tested it using the Green Wire (12v from ECU) to energise it, (with a volt meter on it as well), when disconnected the 12V dropped out. Thanks Paul | ||
| James Selevan (Jselevan)
Member Username: Jselevan Post Number: 421 Registered: 6-2002 |
Paul - I tried to follow your excellent description of the problem/solution. Without a schematic it is a bit difficult. Are you sure that the high/low pressure switch on the dryer is not shutting off the system? Has the filter/dryer ever been change? Over the years the filter/dryer will collect debris that will increase flow resistance and subsequent pressure. I have found similar symptoms, and nearly similar electrical diagnostics with a high-pressure switch opening from an old filter/dryer. For what it is worth. Jim S. | ||
| Paul Hill (348paul)
Junior Member Username: 348paul Post Number: 87 Registered: 12-2002 |
Phil, I did mean to mention that fact that the diode is about 2mm in diameter but part of it sits in the recess underneath. It is hardly noticeable. I have found a source here in the UK with the diode inside the relay.(And the right way round!) http://www.vehicle-wiring-products.co.uk/VWPweb2000/relays/relays.html Quote from the site " These relays have a diode in the coil circuit to protect against voltage spikes in sensitive circuits" The ref number is 72714 and they cost �3.82 each. And at this cost it is probably easier to buy one!! Still, at least it proved the point! Good Luck. Paul | ||
| Phil Good (Feelnotbad)
New member Username: Feelnotbad Post Number: 7 Registered: 1-2003 |
Paul, Once the diode is in place, can you put the relay back on his socket? How thick is the diode? | ||
| Paul Hill (348paul)
Junior Member Username: 348paul Post Number: 86 Registered: 12-2002 |
Phil - Hold on!!! The plot thickens!! The aftermarket relay I bought had a resistor across the coil contacts - This does not stop all the back EMF. It helps but it still happened every now and again. The gold Relay that James is talking about has a diode across the coil to stop all the Back EMF. I had a look in the parts list and they specify the same relay for all the sockets!! I presume Ferrari Part Dept must know about this. I don�t know what they charge for it, but if you cannot get hold of one, there is a very simple mod that you can do to the existing relay. The diode is a 1N4001 � they are very cheap pence/cents each. (Radio Shack/Maplins etc) .All you need to do is solder the diode underneath the relay on pins 85 & 86. One very important piece of information. THE WHITE BAND ON THE DIODE MUST GO TO THE POSSITIVE SIDE Pin 86 on my 348 If it goes the other way it will create a dead short and blow a fuse. To be 101% sure just check the socket in the fuse box to which one goes to earth. (Should be 85) Picture paints a thousand words as per usual!!! Paul  | ||
| Phil Good (Feelnotbad)
New member Username: Feelnotbad Post Number: 6 Registered: 1-2003 |
Great finding. I had the same problem. I know where to rush on Monday. Many, many thanks for this post. | ||
| Paul Hill (348paul)
Junior Member Username: 348paul Post Number: 85 Registered: 12-2002 |
Thanks Jeff, The wealth of knowledge on F-Chat � (well 99% of it anyway!) is quite remarkable. I just like to give back a little what people have kindly shared from over the years. James, I wish Ferrari had told me about it in my 1994 Workshop manual!!! On second thoughts - it would have been too easy! - We all enjoy a challenge from time to time!! - Thanks for the info. Paul | ||
| James J. McGee (Dr_ferrari)
New member Username: Dr_ferrari Post Number: 45 Registered: 7-2002 |
Paul, Ferrari on the newer 348`s changed that relay due to that particular problem. They did send a TSB to the dealers I believe in 1992. The newer relay is in gold color. Good job finding that fault... Regards, Jim | ||
| Jeff Edison (Euro308guy)
Member Username: Euro308guy Post Number: 258 Registered: 7-2002 |
good post! | ||
| Paul Hill (348paul)
Junior Member Username: 348paul Post Number: 83 Registered: 12-2002 |
I have had a problem on the 348 ever since I had it where by you would turn on the A/C and it would work for about 5 mins, then the air would start to get warmer. The only way to get cold air again was to turn the A/C off then back on again. It would immediately get cold again for 5 mins and then start to warm up again! I have spent all day on this and finally found out what the problem was! I put the test lamp on the 12V to the low/high pressure switch to see when the Clutch was engaging. And also one on the medium pressure lead to see when the fan would kick in for the condenser. With the clutch engaged and the medium pressure switch closed circuit, the fan kicks in � All OK so far � suddenly after about 40 seconds the clutch and fan loose the 12V. Checked the hot side and no 12V there either! � Re-start the A/C ad the 12V is there. The problem was the relay coil � When it was de energising there was a huge amount of back EMF from the coil that the ECU did not like and would shut down the 12V, but without any error message. The relay that controls the condenser fan is one of the metal can �Bosch 30 AMP� type � Relay location is �C� in the front fuse box. I replaced it with a new aftermarket type relay and have had no problems � To be 101% sure I replaced it with the old one and it took out the 12V from the ECU after the first time the condenser fan turned off. Ahhhh !!! Paul |