Mondial side marker light

The front side marker light on the driver's side is not working -- the other 3 work fine. I checked the voltage at the contacts and it is about 12 volts shy of the ideal. Does anybody have any tips on how to trace this to its source on an 86 Mondial 3.2? I tried to see where the cable goes, but it isn't obvious. The wiring itself appears to be in great shape.

 

Did you check/replace the bulb ?

 

Just to save a lot of time, make sure it is not a ground problem. Check the voltage and pick a known good ground not the lamp socket. If it is a ground problem you just need to do a little cleaning.

The wiring diagram top view shows the wires to go into a harness that swing forward and around to the right headlights and then to the left headlights near the bumper. See enclosed pic but it may not show enough resolution.
View attachment Untitled 2.pdf

 

Tom -- the bulb checks out an ohm meter and I swapped with the passenger side and it works there, so the bulb seems to be okay.

Karim -- thanks for the tip on the ground -- I will check it out. Also, thanks very much for the wiring diagram

 

Following Karim's advice, I verified that the ground is okay and was able to trace the power wire to the harness where it plugs into the fuse box. I tested the wire with an ohm meter and it is good up to the plug. I then removed the fuse box and back panel and the wire has connectivity to the solder joint on the green circuit board on the back of the fuse box. So it looks like the problem is internal to that circuit board (or behind it, I didn't remove it to see what's there). It looks like there are about 10 screws holding the circuit board on but I'm a little reluctant to remove it. Does anybody know if the circuit board is easy to remove and put back together? Is there anything else I should be looking at?

 

Peter,

I went to check my Mondial wiring schematics to look at how the marker lights are wired. Surprise! They aren't in the schematics. No marker lights.. Must be a USA supplement or something that I don't have.

So, are all four marker lights wired to the same point on the plug that goes to the fuse box? If so, how could only one be inop. If each of the four marker lights go to different pins on the plug that would be very odd...

It seems to me that the way it would be setup is for the fuse responsible for the marker lights would have a trace (in the fusebox circuit board) to a pin on a connector which then feeds the harness to the marker lights.

If you know which fuse supplies the marker lights, what does a continuity test tell you between the fuse and the pin on the connector?

It just seems hard to believe that Ferrari would take power from the marker fuse and then branch it to four different output pins (maybe 2 for right/left but then you would be out 2 lights not just 1).

 

Peter,
I had a variety of problems on my Mondial t side (marker?) lights and indicators (or is that marker). Anyway, all the problems were down to dirty recepticles for the bulbs and dirty contacts in the wiring plugs which the lense wiring harness plugs into. A good clean up with scotch brite and a coat of Stabilant 22 fixed the problem in all cases.
Terry

 

Good questions. I wasn't too clear in my post. I traced the wire to a large 4 inch white plug of about 15 electrical connectors. There is a separate large connector for the left and right side (they are located vertically on the left side of the fuse box under separate large red wire plug for each). I am not sure how these connectors are wired to the fuse -- I think that takes place on the circuit board -- all I can see is the back of the board where it is soldered because I haven't yet tried to remove the board. The marker light wire is blue with a white stripe and I can see where the wire for the passenger (that works) is. The "easy" fix would probably be to solder a wire on the back of the circuit board from the passenger side light to the driver side -- it is only about 1 inch away -- but I would rather fix it the right way if possible. I did try cleaning and spraying all the connectors without success.

 

I've taken the fuse box apart before. It is a multi-layer pc board so it is not simple to follow the traces.

If I understand you correctly your saying that power to the marker lights are on four separate connector pins to the various sides? Are the marker lights served by one or two fuses (one for all or two for right/left)? Pull the fuse and do a continuity test between the fuse pin (not feed side) and the connector pin. A cracked trace is always possible, but I can't imagine that the setup is four individual pins. Another thing that could be is that the actual pin in the connector has cracked away from the circuit board pad a bit, which is easily fixed by re-soldering the pin. You just have to pull the plastic back off the fusebox rather than pull out the circuit board to do it.

Is your fusebox the newer ATX style or ceramic style?

 

Checking continuity from the fuse block to the lead is a great idea -- I will give that a try tomorrow night. I did have that panel off the fuse box and I can see a slight break in the solder, but there is continuity between the back of the solder joint and the marker light socket so I thought it was good. Testing from the fuse block to the solder will test the other side of the link. There are at least 2 connectors for the left and right -- I haven't tried to trace the rears to see how they are wired to determine if the total is 4 or 2 (I assume 4 since the rear driver driver side works and the front driver side doesn't). I don't know whether the fuse box is ceramic or ATX -- how can I tell? I know the early Mondials had a lot of fuse box issues, but I think the 3.2 had a different version that is more reliable -- I haven't any electrical problems up to this point. Thanks very much for you help.

 

I checked continuity from the relay wire to the circuit board and it looks it's 3.6 ohms on the good circuit and 16 ohms on the bad one. It looks like I will need to take it into the shop.

 

Congrats on finding the problem. Sorry it wasn't an easy fix.

 

Why not just wire in a quick splice from the known good circuit over to the "dead" one? Not elegant, but if the film circuit board is bad on the fuse panel, the only alternative may be a very expensive replacement....

 

Karim -- thanks very much for your help -- I wouldn't have made to this point without your help.

Dave - I've been on a mission to fix it the "correct" way -- but you are probably right that relplacing the circuit board/fuse box is a little extreme for a side marker light issue. The front parking light cable connector is within inches of the marker light -- I'll see if I can find a matching connector so I can try splitting that connection to the marker light (I refuse to cut any wires, but will try this if there is a clean way to do it). Thanks for the suggestion.

 

Peter,
FYI. A side marker light is one of the more reasonably priced Ferrari parts. Probably because it came off of a FIAT. I just got one at WWoC and it came complete. Lens and socket with connector. Cost was only $30.00.