Headlight door tutorial

carl

carl

True Classic
Just point me to the proper previous discussion. Plugged in all the headlight fuses on the 77 and turned them on. Lights come on high and low beam. Doors will not open. If I open them manually, they close immediately when I turn off the power. So clearly this is an opening issue.

Notes from previous owner indicated he had the same problem so it wasn't something I did.
 
Seems that type of issue is usually the diodes for the electric motors (that open and close the units). There are two diodes on each unit and the various combinations of any/all of them burning out can cause a bunch of different problems for either/both doors.

Here is a nice write up on replacing those diodes:
http://www.visualimpressions.ca/fiat/diodes.htm

Thought I had some discussions on it linked but don't see them now.
 
Dr Jeff maybe right (don't laugh, it could happen, like once in a lifetime), the diodes are often the problem, but first check the fuses and swap the relays. IIRC the 2 small fuses are one for each headlamp. So if they are closing, they are fine. I'm in the process of repairing one diode. Mine is opening but not closing (other side is fine). But I got problem finding new diodes. My previous supplier closed his door 10 years ago and the others I found are BO for unknown elay. So I'm prepairing to order NOS from eBay at 5 time the price. Or I may take my time. My car won't hit the road this summer, still too much job and not much time.
 
Daniel Forest said:
But I got problem finding new diodes. My previous supplier closed his door 10 years ago and the others I found are BO for unknown elay. So I'm prepairing to order NOS from eBay at 5 time the price.
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These diodes are a very standard component - anything rated for 12 volts and a few amps will work just fine. The last time I needed some, the local Radio Shack was still in business and had them.
 
I had this problem and Walter adjusted something and now they work. Talk to Walter. I do have some spare motors if you need them.
 
here is a LONG string where I had issues. READ IT ALL as the diagrams at the beginning were not right. the message below them will say it isnt. EricH Kicks butt when it comes to this. He explained it very easily. there are links to many resources.
I ended up pretty much rewiring the entire circuit. and know these pretty good now. Totally agree with starting simple and seeing where you have power when.

https://xwebforums.com/forum/index.php?threads/po-headlight-issues.31000/page-2

Odie
 
EricH said:
These diodes are a very standard component - anything rated for 12 volts and a few amps will work just fine. The last time I needed some, the local Radio Shack was still in business and had them.
Click to expand...
Nice to know. I used to buy them at Radio Shack (now under another name and not selling these anymore), in 1kv 2,4a. I'm willing to fit a different diode, but I'm not sure about what is the acceptable range. My electronic knowledge is pretty limited. Especially like when the dealer ask me how many ohms I need... :oops:
 
carl said:
the "up" short fuse was too loose in the holder
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Those "short" fuses are hard to find anymore. With the old style fuse box they can be replaced with regular length fuses by simply bending back the 'tabs' that hold them. That also makes them fit tight, so they won't come loose and cause these problems.
 
Daniel Forest said:
Nice to know. I used to buy them at Radio Shack (now under another name and not selling these anymore), in 1kv 2,4a. I'm willing to fit a different diode, but I'm not sure about what is the acceptable range. My electronic knowledge is pretty limited. Especially like when the dealer ask me how many ohms I need... :oops:
Click to expand...
The most common rectifier diodes are probably the 1N400x series. They all handle 1A of current (plenty, if not overkill, for driving the relays in the X1/9 headlight control). The diodes in the series differ in how much reverse voltage they can handle without breaking. The 1N4001 can handle 50V, which is a bit low for the harsh electrical environment of a car. 1N4002 and up are adequate, but given that these are essentially free (<< $1 at DigiKey) I would get the 1N4004. If you order from DigiKey, choose the "Cut Tape" Packaging option. "Bulk" works too, but there is less selection. Any manufacturer is fine, whatever is in stock at a price you like.
 
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