mounting external relays for headlights

[MikeT 744]

As you may know, last week my smart Canada 1 had what I thought was a burnt out right headlight. I changed the bulb the next day and....hmmmm...still out. Checked fuse 22, nope, it's fine. Conclusion: SAM failure in that circuit or maybe a melted connector, or both.

The good news is that the left headlight was still working. So my plan was to use the one "good" headlight circuit to run both of them, if the right headlight circuit in the SAM was dead.

I pulled the SAM down (two T-10 screws hold it in) and pulled out the N11-3 plug. It was melted on the two central pins (as well as the one that runs the fuel pump, which was previous damage).

The SAM also showed heat damage on the two central pins:

My SAM had been replaced at my cost in 2013, 26 months ago in fact, but the parts warranty was up and that's that. The dealer in Victoria, Three Point Motors, kindly offered me a free repair harness for the N11-3 plug (usual cost is about $60). I had some Hella 30A relays and bought some shrink wrap, an inline 30A fused link and some corrugated wiring sheathing in the smallest available diameter.

The work was done Saturday.

The first thing to do is to undo the plastic rivet holding the felt under dash panel in place, which makes the wiring job easier.

The repair harness had an identical plug (brown) to the one seen two photos above with the melting damage, but the wires were all different colours and in different positions. Plus there was an extra wire. So splicing this into the car's harness was not only unnecessary, it would have been impossible using the pigtails that came with the repair harness. The thing to do was to remove all wires from the repair harness plug and then insert the ones on my car. So I did.

The was the first step in diagnosing whether the right headlight circuit within the SAM was actually dead or not.

The wiring connectors are freed from the brown plastic plug by gently prying up the side cover plate on one side of the plug, which is a secondary method of retaining the connectors within it, and then gently lifting the little brown plastic barbs that hold the pins in near the end. I took one out at a time, of course being careful to insert the removed plug into the same position on the replacement brown plastic connector. After this was done and the plug's side cover was snapped down again, it was reinserted into the SAM and I tried it out.

The right headlight still did not work. But was it the SAM or the connector in the plug? I then unclipped the dead wire and cut it off about 6 cm above the connector. I then got a new connector that I had removed from the harness, cut it and soldered it inline. Reinserted into the plug and - it worked! So the SAM is not grievously damaged!

I did the same to the "good" connector for the left headlight, in case it had some residual damage as well.

The plan, now that I knew both headlight circuits were OK, was to run a single 12 gauge wire from the positive battery terminal to the vicinity of the SAM, where it would be soldered to a 30A inline fuse holder (I used a 25A fuse, which is probably still too large!) , then it would branch into two in order to provide the external supply to run the lights. I would mount two 30A relays next to each other near the SAM, one for each headlight (overkill, but redundancy is good). The 12 gauge supply wire from the battery was inserted inside a metre long corrugated plastic sheath (to prevent chafing) and threaded through to the driver's side using the space just behind the "firewall". It was zap strapped to the hot terminal on the battery to ensure it stays in place.

A "Y" piece of wire was fabricated for the relay grounds and I secured both relays to a piece of drilled metal strapping.

The next task was to take the power leads from the SAM and splice in a connection for each relay. For this purpose I used the removed wires from the new N11-3 harness, so they matched the colours of the originals. It was simply a question of soldering the new wires inline with the cut I made in the old ones (about 15 cm back from the connector) and soldering a connector onto the end for the relay. Then the lead from the relay to headlights had to also be spliced into the original wires. You will notice that I made insulating sheaths for each connector, you can never be too careful!

Once that was done, the metal strap the relays were attached to was bolted to the large ground bolt above the dead pedal. Make sure that the grounds that were there are attached when you bolt it down (if you use the same technique as I did to secure the relays), as well as the Y-wire used to ground the relays.

And that was it, the SAM was bolted back into place, the felt under dash panel was clipped back into place using the plastic rivet. A test showed all is well.

[MikeT 744]

Having experienced this problem, I highly encourage everyone who has a 450 to do this for the headlights and also the fuel pump. It's only a few hours of work for a loafer like me and will save over a thousand dollars if the SAM were to fry because it wasn't done.

[CANMAN 23]

Good job Mike.

You didn't need to run a separate power wire from the battery, you could have gotten power from the extra fuse holders on the side of the SAM.

What about the fuel pump, aren't you going to use a relay to prevent damage in the future?

Canman

[MikeT 744]

The fuel pump has had an external relay since August 2013. That one uses a spare fuse from the SAM for power; Three Point Motors did that job.

I wanted to do an external wire because I don't trust the damned SAM! Not being sure how those spare SAM fuses get their juice, I wanted a direct supply.

[tolsen 630]

Special sockets are available for these relays at no major cost. Less chance of terminals coming off and no guesswork when refitting.

[MikeT 744]

These ones won't come off, ever. When I test fitted some of these German-made spade sockets onto the relays, I needed pliers and a large amount of force to get them off.

[SmarteeBluey 10]

Great job Mike.

I did that 2 years ago hear in Aus to my 450. Don't know why, but have not had a blown headlight since either.

[flekker 10]

I know this is an old thread but is there a wire diagram for this.  I am a bit confused on the power and head light feed wires on the sam.
 

[Willys 747]

25 minutes ago, flekker said:

I know this is an old thread but is there a wire diagram for this.  I am a bit confused on the power and head light feed wires on the sam.
 

You cut the two wires that feed the lights on the n11-3 plug, I believe they are the two middle ones, right and left. They now signal the relay not the headlights. The relay is powered by the battery and then powers the headlights.  Research the correct wiring diagram for your relays on youtube and it will show you which wire to hook to each terminal. I just did mine, for both low beams and fuel pump. The other bad apple in that row of pins in the SAM.  You can run a new wire directly to the lights or simply use the other side of the cut wire at the SAM that runs to the lights after the new relay.  That wiring diagram I just sent you will show you which wires go to what so you can see what colours they are from that. BUT, also check your SAM for hair line cracks around those 3 pins. You may require a magnifier of some sort to easily see these cracks. They also will be in a circular direction around the centre pin. It occurs from the pin heating up and cooling too fast and the solder cracks because of this. You need to remove the old solder using a solder sucker or wicking copper braided wire and then do a clean re-solder job on each pin. I highly recommend using a modern high heat soldering iron so you do not over heat the board trying to get the solder to liquify using the older slow heating irons.  Also check plug for over heated signs, it happens.

 

 

Edited August 25, 2021 by Willys

[flekker 10]

Thanks Willys.  I was looking into my headlight wire harness and based on what I found it was a hack job on both sides.   The wires coming from the N11-3 pin for the head lights are disconnected and taped off at the head light harness.  There is a Brown/blue wire being used instead, i think its coming from that stupid transport canada module.  If i hook up the wire that is coming from the N11-3 plug it get the light to work but no running lights. 

 

[Willys 747]

I think the running lights are on a different wire, check that diagram I sent you it should tell you.  Sorry don't have my book in front of me at the moment.

Also have you opened up that transport can box yet to check it's condition....mine was fuzzy and also the plug.....it is easy cleaned as it has no capacitors inside it to flash like the ECU does! BEWARE!  There is also a little white connector in the front of the battery box/well that is bad for going green and you simply cut it out and hard wire the wires.  All done with battery unhooked just to be safe.

 

Edited August 27, 2021 by Willys