Instrument fuse blowing and alternator stoping

I do not know how it works in the US but over here we hand in the old alternator and they give you back a complete new one with 1 Y warranty. It is actually quite cheap if you do not mention it attaches to a Ferrari.

 

Sounds typical of a socialist country

There is nothing presumably wrong with the alternator itself; so I am replacing just the regulator. Didn't even take the alternator off the car....

 

What brand is the alternator itself? A valeo?

Sometimes the regulator is integral to the alternator.

 

Nippondenso. Regulator is easily removable; you just have to FIND another one

 

IN265 - Voltage Regulator for Denso Type Alternators - 12 Volt, A-Circuit, 14.5 Volt Set Point, P-IG-L Terminals

 

Okay Dave, stupid question.....
The original regulator for the OEM alternator was the Transpo IN220, not the 265. That original regulator has S-IG-L terminals on it. I know that there are MANY regulators that CAN be used, is there a specific reason you listed the IN265?

 

Luke, come join the dark force of socialism. Swap the alternator as a whole....stop trying to find the regulator force...

Oh, and bring your sister.

I think he is referring to IN265 cause it is the right piece for the John Deere, which is what you need for the tractors we drive.

 

I'm not really sure about the 265, that's what is listed on one site. I do have a IN320 on the shelf along with a brand new Amazon RE5002260 alternator by Rareelectrical.

The regulator I have in my Denso 101211-7780 is a "soft Start" but I don't know the number. I think its a Transpo but I'm not sure.

If I were you I'd call Quick Start Automotive Electric at 1 (616) 606-5045 and ask them about a soft start regulator for a Denso RE5002260 alternator.

The quick start doesn't give full output until about 8 seconds so there is no danger of over voltage damage to ECUs but occasionally you will get an alternator light for a few seconds.

BTW, I just found a new "Real" OEM Denso 101211-7780 alternator on eBay and bought it for a spare. I believe this is what you have Pete.

 

Good catch, Dave!
My new regulator arrived today and after installing it I discovered that the old regulator is not the problem.
The fuse blew again upon turning the key.
At this point I'm going to begin to search for the short using a signal generating short detector. I have never used one of these, so it should be interesting
It is going to rain here this weekend, sounds like a good time for some garage work.

 

I know what the first word out of my mouth would have been.

 

Pete, you said you unplugged the regulator and got no blown fuse which would indicate a short in the somewhere in the alternator but not necessarily in the regulator.

Make sense????

 

I am still going with the alternator.

A short in one of the diodes.

you can test that with a multimeter but you will need to dissasemble.

http://www.youtube.c...bed/xgikeXt91vM

 

Yes Dave, makes sense. Except.
Once I put the new regulator in and plugged everything back up, the fuse blew. With the one remaining fuse that I had, I've been unplugged the regulator harness again, and the fuse still blew.
No, I don't have a good explanation At that point last night, I recognized two things: one, I have a full-time job and chasing a short on a work night is not it. Two: I was out of fuses again.
Before I "discovered" that the regulator might be the problem, I went through 15 fuses trying various things. The fuses all blew every single time except for when I unplugged the regulator. Once I get another supply of fuses, i'm going to heed Carl's advice about not guessing forever and taking a more scientific approach. ;-)

 

Pete, by disconnecting the regulator harness, and seeing that the fuse still blows, IMHO you've effectively eliminated the alternator as the "bad actor", however if you want to make doubly sure, go ahead and disconnect the heavy +12 lead on the output stud as well as the regulator connector. I think you'll still have the same result, but then I've been wrong before......

Your troubleshooting isn't really haphazard at all, because none of us really know which loads are on that 7.5a fuse. One thing you could do which will save you a lot of hassle and fuses, would be to leave the fuse out of the socket, and connect a low wattage filament type lamp to the load side of the socket and +12v to the other side of the lamp, and watch it as you disconnect various loads. Note, it needs to be an old style filament lamp - not an LED type lamp.

The theory here is that you have an unknown path to earth somewhere in that harness, so by putting that lamp into the circuit with +12 on one side, and that unknown earth on the other, it will light up. You may have to play with different wattage lamps to get a satisfactory illumination to work with, however.

As you disconnect "good" loads from the circuit, the brightness of the lamp won't change (because the good loads are not going to earth). However, when you find the "bad actor" and disconnect it, the lamp will either go out, or the brightness will drop significantly.

If the thought of putting a lamp in that circuit makes you nervous, you can attack in a similar, but different way with your DVM. Put your DVM on ohms, and put one lead on the load side of that fuse socket (still no fuse in the socket), and put the other lead on a good ground (like the battery negative). Then start disconnecting loads and watch the DVM. When you find the bad actor, the DVM resistance reading will "increase", ie there will be more resistance to earth.

Note, both testing methods should be done under the same conditions as when the fuse blows, ie ignition key on.

The disadvantage of the DVM method is that if there is a relay in the 7.5a fuse circuit that gets energized when the ignition key is on, it will not energize when you're testing with the DVM.

 

John, I believe there is a relay on that circuit, it is called "Under Key Service" or key-operated controls (from the WSM). Going to do some more troubleshooting this evening before I use the signal generator.

 

I have solved the problem in my 550, and the source of the electrical short is pretty fascinating. Every 550 owner needs to read this thread at some point to save themselves thousands of dollars of "diagnostic costs"

Any guesses? Thread will be updated later tonight with photos!!!

 

Luigi left his gold necklace in the alternator housing during assembly and now it shorted?

 

A bad relay?

 

I decided to approach this problem more systematically, with the help of my friends John and Carl. Thanks guys.
I purchased the ECT2000, which is a signal generator device that is designed to "inject" signal into a shorted circuit and then uses a receiver to follow the short around the car.

First step was to isolate the load terminal of fuse number 5 (Photo 1)

Second step was to plug the ECT2000 into that load terminal to verify the short was present continuously (the device sounds a continuous tone), and then unplug individual wire bundles that leave the fuse box one at a time to see when the short is no longer present (tone stops). The first harness I tried was the one. I then used a digital voltmeter to find which terminal from that harness was continuous with the load terminal of fuse #5. It turned out to be the 6th spade terminal in (Photo 2)

Now that I have localized which wire is shorted, I can plug the ECT2000 directly into that harness, figure out what items are connected to that wire, and then try to trace the short signal through the car. (Photo 3)

Finding out what is on the circuit is an exercise in futility. The 550 WSM is virtually worthless. However, what was NOT useless was the WSM for the 456M, which has a vastly superior electrical diagram section. I was gambling that there was lots of commonality between the cars, and I wasn't disappointed.
Using the WSM, I made a map of everything that this wire appeared to connect to. There are a number of spliced interconnects as well, which made it quite complicated. Here's a basic outline (Photo 4)
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Now I was able to use the ECT2000's receiver to try to trace the short...it is challenging, as there are several "false positive" readings as wires cross over each other, but eventually it appeared that the short was carried through the firewall into the engine bay on this harness (Photo 1).

Unplugging this harness stopped the fuse from blowing when the key was turned.
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Of course, the harness involved has to enter the engine bay UNDER the battery (major pain) and branches off into about 5 different bundles, but using the signal receiver I was able to trace the short signal to the following item (Photo 1)

Removing the connector from this sensor removed the short from the system. It even has the correct color (green with white stripe) wire entering the sensor in the left most position (Photo 2). This sensor sits just forward of the harmonic balancer on the back side of the radiator.

Now this sensor is NOT a "lift" sensor. It is labeled as a vertical accelerometer, I am guessing to help the ASR system? It is not clear from the WSM what exactly it does. I have removed and replaced this sensor several times in the past during majors as it frees up space to get the impact gun on the crank bolt, and have noticed when I took it off that it has a small metal "brick" inside of it that rolls around inside the sensor if you don't preserve its exact orientation when you remove it. NORMALLY, the inside of the sensor looks like this (Photo 3). Notice the little gold brick sitting under the contact point, and there is a very small gap between the contact and the brick.

After removing the sensor from my car and carefully preserving its in-car orientation, I opened it and found this (Photo 4). The metal "brick" has fallen off its surface, and is shorting the leftmost terminal to the screw in the photo. This leftmost terminal is the green/white wire in the harness.
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When I removed the brick, I found witness burns on both the brick and the involved terminal. This is clearly seen (Photos 1 and 2).

I replaced the "brick" in its correct position, and proceeded to coat all 4 terminals and the screw head with a thick layer of silicone caulk, to serve as an insulator if the brick ever slipped off again. One can see in the previous post that Magneti Marelli put a huge dollop of silicone on the other terminals inside the sensor, so I reasoned that more silicone on the other terminals would work. Theoretically, as long as the sensor stays securely bolted to the car, the only way to displace the brick is to turn the car over

No I don't know how this happened with mine....

Once the sensor was reinstalled and everything reassembled the car runs as normal and no longer blows its number 5 fuse. Time will tell if this problem recurs; hopefully my silicone fix will do the trick.
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Great job. It's so satisfying when you are able to find a problem and fix it on your own, especially after a few unsuccessful guesses. Finally seeing with your own eyes the problem is a great feeling... that is as long as you can then fix it!

 

moorfan

I'm impressed...nice work

 

Pete Pete Pete...you just don't understand Italians. What you did was trigger the "high G force overload trigger." Shame on you for driving your Ferrari as Enzo intended. The silicone application will now remove this important safety feature...