Electrical gurus needed

In mid April I put 1200 trouble-free mkiles on the 1994 512TR in one week. When I next went to start it - NADA. The starter was fried and melted. Some quick diagnostics found I was getting 6 volts to terminal 50 with the key in the run position, presumably not allowing the starter to fully disengage. I did not notice/check if any other systems were off. I had 6 volts at the "I" and "F" connectors, pin 1, when attached to the board, but 0 volts at the "I" connector, pin 1 with terminal disconnected from the board. I figured the ignition switch was ok, so I ran a jumper from the "i" to "F" connectors, pin 1 terminals, and the new starter functions well and the car runs.
I then noticed that the AC controls, turn signals, wipers and glove box actuator did not work.
I found fuse 6 on the Dave Helms fuse box modification was blown, so I just replaced that, but still no go (listed as fuse to AC condensor motor). Is there a relay associated with this fuse, and could the above scenario also fry the relay? Or could it be a malfunction of the ignition switch itself? (best price on a 12K mile used unit - $1800). All other functions in the "run" position work fine (dash lights, head lights, radio).

I guess my questions are these: 1) - could re-connecting connector "I", pin 1 to the connector and the fuse box possibly fix the problem? Since it has 0 volts in "run", I don't see how. and 2) - could a starter motor left engaged to the flywheel and spinning and ultimately frying somehow cause a short backwards through the fuse box?

I have a call to Dave Helms also for his advice, which I will post. I have some exigency in this post, as I am scheduled for my annual drive to Sandestin FL on Sunday (7 hrs each way) and turn signals and AC would be nice to have). Thanks.

 

How many amps is the fuse you replaced? More than likely, if it isn't some high amperage fuse, it goes to a relay. Most everything you note (AC, turn signals, wipers, and actuators) probably has an associated relay.

Regarding the starter motor, yes, it could act like a generator and that would be bad. Is the old starter motor stuck in a way that would have made it remain engaged?

 

This is best answered by photos:
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Here is my admittedly amateur thinking.
My last drive before I noticed the starter failure was approx 1.25 hours. I noticed no malfunction during the drive, and I'm fairly certain the AC would have been on, and I'm completely certain the turn signals were working all the way home, so I'm puzzled as to when this circuit malfunction occurred. The next time I tried to stat the car there was no response (obviously - see photos above), and all repairs were made with the main power disconnected at the shut-off switch.

Years ago I had installed a relay at the starter to fix a no hot-start problem (I mean 35,000 miles ago). That relay still functions perfectly. In retrospect, a 6-volt bleed-through could have been enough to activate the relay and fry the starter (my bad).
Could the spinning starter act like a generator and send a power spike back through the relay (30 amp) and into the fuse box? If so, why would it blow the fuse to the AC condensor fan (as far as I know, an isolated circuit)??? The common point in all these circuits is the ignition switch in run position, except for the starter, which is only energized in the "start" position. Other circuits on the "run" position of the ignition switch still work, and the car runs normally. Of course, knowing ferraris, these could be two random isolated problems happening simultaneously (doubtful). There must be a relay controlling power to the glove box, wipers, turns and ac evaporator, right?
Is my reasoning so far at all correct?

 

I can't say if it is correct but it is possible.

 

I think you would have heard the starter motor spinning if it had not dis-engaged. My guess would be the relay that you added had bad contacts after a couple of thousand starts and arc-welded the cotacts and allowed the starter solenoid to remain energized but at a low voltage. The starter relay that somebody installed in my 348 used a huge contactor style relay not a bosch cube relay. The blown fuse could be part of the TR quirky-ness. Just a 7 am thought with only one cup of coffee. FWIW.


Jeff Pintler
89 348tb,86tr, 99 360 3-pedal

 

An engaged starter would have desintegrate by overspinning and it doesn't look like it. Here is my thinking.
The pull in winding in the solenoid is supposed to be Under load for a fraction of a second. It is a high intensity coil and it becomes inactive when the solenoid contact gives positive to the starter motor stud because the pull in winding get its ground through the starter motor itself.
If after you started the motor you had a constant 6 volt on the solenoid positive terminal it was not strong enough to keep the solenoid engaged or pull the solenoid and the motor was there as the negative path. For this reason you never heard anything wrong and the current in the pull in was constant and fried the winding.

 

Good thought, Jeff, but the relay still works fine. Unfortunately my last start before the starter malfunction was at Sebring Raceway during the 12 hr International race. I was 100 feet from the track, where you can't even hear yourself think. And besides, my car is kinda loud with test pipes and hollowed-out pre-cats. The Bosch 30 amp relay has functioned fine for over 35,000 miles, but it's coming off anyway. I agree with the fuse being just quirkiness.

 

You may be right, GBI, but Mr Willie, owner of Trail starter and alternator, took one look at it and said it got stuck engaged and fried (see photo). When I put the new starter in, before touching anything else, it also would not disengage and did make an awful whine. I stopped it immediately and then began the diagnostic investigation.
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Let us know what you find!

 

I don't get it. It makes no sense. I fixed it.
After removing the fusebox and the control panel bracket behind it and checking EVERY fuse and wire and connection, I still had no power to the wipers, ac, turn signals and glove box. I again looked over the parts manual and the workshop manuals (insanity). I then remembered Jimbo's Prime Directives when working on a Ferrari:

1. Ferraris don't conform to the laws of physics and the known universe
2. If something makes absolutely no sense, try it anyway, it's probably right.

I had removed the white wire from Connector I, pin 1. It comes from the ignition switch with 0 volts in run and 12 volts in start. It then runs through the fuse box (no relay) helter-skelter and exits as the white wire on Connector F, pin 1 and then merrily out to the solenoid (terminal 50).
Therefore, one would logically postulate that removing said wire from the connector would not affect anything in "run position" since that wire carries 0 volts in "run" position.

Not so, grasshopper! Let us recall Jimbo's Prime Directives above (Ferraris make no sense). I reconnected the white wire from the ignition to the Connector I and the fuse box and behold - all systems are now functioning properly. Why? How? I have no idea.
All I can say is "It's a Ferrari".

I took the relay off the starter, so everything is now in origional configuration and magically, it all works.

I am leaving tomorrow AM on a 7 hour annual excursion to the golf/beach resort of Sandestin in the Florida panhandle, so all this came together at the 11th hour. When I get back I will check voltages at all the terminals and report back.

The blown fuse for the ac condensor fan was indeed a red herring and had nothing to do with the starter issue. Man, this stuff makes me crazy.

Thanks to all who gave souns advice.

 

voltage drops are serious especially when it comes to starters and other heavy draw motors... check all the cables and connections... starters only care about watts or the grunt needed to start... it's simple electricity... as the volts go down the rest of the watts demanded is made up by drawing more amperes... more amperes need thicker cables and better connections...failing that, a lot of heat is generated by undersized wiring and bad connections... leading to the mess you are describing... things get burned up...

start with the battery... an out of spec / weak battery not able to deliver the required spec can be a part of the cause...

the equation is watts equals volts times amperes... fill in the blanks

 

this car is subject to a super ceded P/N for a starter motor with solenoid unit...clearance on these is quite tight as I recall, been a number of years frankly, but I do remember that there was a specific notice in the parts computer-MEDEA it was called at the time...
New motor was of a newer design, and of Japanese mfg if memory serves...

 

Understood. The battery is brand new, all connections are clean and tight. I suspect the problem lies within the circuit board. The start circuit comes into the board and then out again with no relay connection, but I suspect the Connector I, pin 1 white wire from the ignition switch also serves to ground the 4 circuits that were no go when the white wire was not in the connector (turn signals, glovebox, ac controls, wipers).
8 years ago I had an intermittent low voltage to terminal 50 (starter), so I traced the white ignition wire from the switch to an ignition kill on the alarm. I soldered all the connections, which helped a little, but my next move will be to bypass the ignition kill altogether and see if that helps. If the voltage drop is within the circuit board (fuse box) itself, I will install a push button for the starter circuit and be forever done with this nonsense.

 

Correct. My starter is a Denso unit (Nissan), very common and cheap ($150). All that is required is to swap the 3-hole flange plate so that it mates to the bellhousing (or pay the F-Pimp $1500 - 2000 for a new unit in a pretty yellow box).
Previous threads that refer to a WAI solenoid upgrade refer to the earlier Bosch unit. My car is a late '94 model (upgraded diff, ABS). I am unsure when they changed to the Nippon Denso unit.

 

Success! I have just now returned from my annual golf/beach vacation and I am happy to report that the mighty 512TR/M performed flawlesssly for all 1144 miles. The starter did hesitate when hot (my first stint was 5 hrs straight highway driving), so I suspect I am back at a low voltage issue. I will have voltage reports after the holiday weekend.
Most of the driving was done in cool conditions, no AC, just cruising down flawless highways at 78-80 mph in 5th gear. I threw in a can of injector cleaner before taking off and I used premium unleaded fuel. MPG was 18.5 with the AC off, 17 with the AC on (85 degrees ambient temp). I use Freeze-12 coolant and replaced the AC compressor, drier, expansion valve and flushed the system 2 years ago. It takes a while, but eventually the cabin gets too cold and I have to dial it back. Another huge help is the reflective film on the windshield which keeps out 99% of the heat (the dash stays cool to the touch).

 

PS: 5th gear equals 2000 RPM at 80 MPH