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No headlights and relay solution


Mocephus
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Hello friends! I recently had the headlights go out again on our 2005 Signature...this time as I was driving to get the state safety inspection completed!

Both times that the headlights failed were due to pins 1 and 2 of the J12 plug on the Smart Wheel controller overheating, melting the plugs and toasting the connection.

I have read that others have experienced a similar problem so I wanted to share the solution I found.

Let me start out by saying that although I am pretty handy and do most of the repairs on our rig myself, I am only dangerously familiar with wiring and electronics so, but for the help of my friends on here, namely Paul Whittle and Rick Pasetto, I would not have arrived at this solution. Thank you very much Paul and Rick!

It has been suggested that the crimps on the Mate and Lock connectors that go into plug J12 on the Smart Wheel controller (found in my front run bay - FRB), may not provide a solid connection thus causing the overheating problem. It has also been suggested that the current load for the headlights is just too heavy for the relays and circuits within the Smart Wheel controller. The recommended solution was to install a relay.

I've wired car radios and even a CB back in the day, but I've never wired a relay, so after lots of research and YouTube videos, and guidance from others, I tackled this new challenge.

In essence, a relay used in vehicles enables a small current flow circuit to control and operate a higher current circuit.

 I bought a 6 pack of type 87 relays and harnesses on Amazon

https://www.amazon.com/dp/B017VDI0GY/ref=cm_sw_em_r_mt_dp_AS2FECW4CDVWRN6JSKRY?_encoding=UTF8&psc=1. These are 5 pin relays, but I actually only needed a 4 pin relay. Relays have numbered connections/pins that I'll refer to later. I did not use the included harness for this application because I wanted to use heavier gauge wires in some instances.

Again, I'm not very electronically saavy so there are probably better ways of doing this but below is how I wired the relay. Be sure to check your own wiring diagrams before trying this.

After killing the power to the FRB, I started by running a heavy 10 gauge wire (red) from one of the big, always on, red cables mounted on the left side wall of my FRB, through a 30 amp in-line fuse (https://www.amazon.com/dp/B08HVQ3575/ref=cm_sw_em_r_mt_dp_31HE8CNDBHMCT8FRVR5F?_encoding=UTF8&psc=1) and then to pin #30 on the relay.

I ran another 10 gauge wire (black) from one of the grounding busbars in the FRB to pin #85 on the relay.

I then cut the pin 1 wire leading into the J12 plug on the SW controller and sealed it off with a wire nut and electrical tape, because I determined with my multimeter that the pin 2 wire is always hot. (NOTE: pin numbers run from left to right when looking at them while plugged into the controller. Also, a description of what the wire goes to is printed on each wire. Ex "HEADLAMP SW" for headlight switch).

Then I cut the wire leading into the pin 2 spot on J12 and connected that wire to pin 87 on the relay. This is the wire that provides current to the headlights. (I have read that some people have run a completely new and heavier gauge wire all the way to the headlights from the 87 pin, but I did not do this at this time...maybe later.)

Next I cut the wire leading into pin 6 of the J11 connector. This is the wire that comes from the headlight switch. I ran that wire into a 30 amp in-line fuse and then to pin 86 on the relay.

I was sure to crimp and solder all of my connectors, apply some dielectric grease and seal them in shrink tubing.

I mounted and plugged up the new SM10 controller that I had ordered, mounted the relay beside it...and called my wife. I told her what I had done and asked her to turn on the headlight switch while I positioned myself near the FRB with a fire extinguisher. I wasn't quite sure that I wasn't about to burn our coach down!

She pulled the switch and BINGO the lights came on. No sparks, no smoke, no fried wires! Yay!

Attached is a rudimentary wiring diagram that shows what I've described above. It was suggested that I also install a relay to handle the marker lights but I'll do that another day as well.

I hope that this information is helpful to anyone who encounters the same problem!

Headlight relay.jpg

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Nice job. I would suggest you don't need 10-gauge wire and a 30A fuse for the coil circuit (85 & 86) on the relay, since it uses very little current. All that does is activate an electromagnet to close the relay. You should always fuse to protect the wire, in this case 14G from the headlight switch so a 15A fuse is a better choice. 12-gauge wire with a 20A fuse would be fine for the headlights. Using a 30A fuse to #30 is way too much to protect the 14G wire to the headlights, which I would replace with 12. 

Something else I have done on past vehicles is to add another relay that uses the high beam circuit to energize the relay, then sends 12V to the low beams. That way you have both high and low beams lit when the highs are on.

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24 minutes ago, Bill Morgan said:

Nice job. I would suggest you don't need 10-gauge wire and a 30A fuse for the coil circuit (85 & 86) on the relay, since it uses very little current. All that does is activate an electromagnet to close the relay. You should always fuse to protect the wire, in this case 14G from the headlight switch so a 15A fuse is a better choice. 12-gauge wire with a 20A fuse would be fine for the headlights. Using a 30A fuse to #30 is way too much to protect the 14G wire to the headlights, which I would replace with 12. 

Something else I have done on past vehicles is to add another relay that uses the high beam circuit to energize the relay, then sends 12V to the low beams. That way you have both high and low beams lit when the highs are on.

Bill, great advice. Thank you!

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Nice explanation on the wiring to separate the headlights from the control module.  I am waiting for the parts to attempt this fix myself and I appreciate the details and the drawing you put on here.  I am also not an electrician but with the great knowledge and advice on this forum I think I can tackle this.  I like the safety advice about the standby fire extinguisher, great advice, Thanks!

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2 hours ago, rpasetto said:

@Mocephus Well done. 

Curiously, I was working on something else in my FRB and noticed that pin2 on J12 is starting to show burn signs.  Another project added to my list.

Ohh the joys of life with a motorhome!

11 minutes ago, StephenW said:

Nice explanation on the wiring to separate the headlights from the control module.  I am waiting for the parts to attempt this fix myself and I appreciate the details and the drawing you put on here.  I am also not an electrician but with the great knowledge and advice on this forum I think I can tackle this.  I like the safety advice about the standby fire extinguisher, great advice, Thanks!

Thanks! I hope it works out well for you!

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I'm ready for more of the joy and less of the fixing.  I replaced the fog lights a couple days ago and when I turned on the switch nothing happened so I started checking voltages in the FRB and found one of the continuous duty solenoids was only putting out 3 volts so I have a couple of those on order. Thanks again for the info.

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As pointed out above, no need for 10 gauge to ground pin 85 of relay, it only operates the coil in the relay, 18 is fine for both 85 & 86. 10 is over kill for supply to pin 30, 12 should be sufficient. Might want to use 12 on 87 to feed headlights.

85 & 86 are the low power control circuit of the relay, 30 & 87 are the load circuit. 

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13 hours ago, StephenW said:

I'm ready for more of the joy and less of the fixing.  I replaced the fog lights a couple days ago and when I turned on the switch nothing happened so I started checking voltages in the FRB and found one of the continuous duty solenoids was only putting out 3 volts so I have a couple of those on order. Thanks again for the info.

Me too!

3 hours ago, Dave Pumphrey said:

As pointed out above, no need for 10 gauge to ground pin 85 of relay, it only operates the coil in the relay, 18 is fine for both 85 & 86. 10 is over kill for supply to pin 30, 12 should be sufficient. Might want to use 12 on 87 to feed headlights.

85 & 86 are the low power control circuit of the relay, 30 & 87 are the load circuit. 

Good info! Thank you Dave!

19 hours ago, Bill Morgan said:

I just looked up the current draw of the coil circuit on a typical 12V Bosch-style relay, which is ~160mA. 18 gauge wire with a 10A fuse would be fine.

The factory wire from the headlight switch (which I connected to 86 on the relay) is 14 gauge. Could/should I go back with something less than a 10A fuse?

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18 minutes ago, Mocephus said:

Me too!

Good info! Thank you Dave!

The factory wire from the headlight switch (which I connected to 86 on the relay) is 14 gauge. Could/should I go back with something less than a 10A fuse?

A 14 gauge wire should be protected by a 15A fuse, 12 gauge 20A, 10 gauge 30A.

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This is a very simple solution to a design problem with the SmartWheel controller, but you lose the ability to flash your headlights with the button on the steering wheel.  The full headlight and current is routed through the controller through J11 pin 6 and J12 pin 1 or pin 2.  The flashing of the headlights is controlled by a module on the controller that operates a dual 25 amp relay,  I would suspect that the connectors that are most prone to failure Re the J11 pin 1 and J 12 pin 1.  J12 pin 2 only carries current when the headlights are flAshed on  during daylight for a short time.  I don’t know how valuable the ability to flash the headlights is important to most people is.  It is something which should be decided to each operator.  From the schematic I have, it appears that the headlight flashing is the only function that you lose by your modification.  Can you confirm?

i searched for the VIP troubleshooting guide but didn’t find it on line.  If anybody would like to have it, I’ll post it when I get to my desktop computer where it is stored.

By the way, on many motorhomes, the headlight wiring is marginal and has significant voltage drops which affect the brightness.  

Dick L  ‘04 Imperial

 


 

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43 minutes ago, Bill Morgan said:

A 14 gauge wire should be protected by a 15A fuse, 12 gauge 20A, 10 gauge 30A.

These are max loads for given wire size, so the fuse protects the wire.

You would fuse according to the max maps that will be drawn from the circuit. 

46 minutes ago, Bill Morgan said:

A 14 gauge wire should be protected by a 15A fuse, 12 gauge 20A, 10 gauge 30A.

 

1 hour ago, Mocephus said:

Me too!

Good info! Thank you Dave!

The factory wire from the headlight switch (which I connected to 86 on the relay) is 14 gauge. Could/should I go back with something less than a 10A fuse?

Yes, that was 14 gauge because it was carrying the load of the headlights, this is the problem. 

Now it is only triggering the relay, a very small load.

18 gauge wire, 1or 2 amp fuse if you want one, really not needed.

Same for the ground side of the coil, 18 is fine.

A 10 gauge power to relay is a bit overkill, 12 would be plenty.

I would use the 12 to the headlights if you are running new wire to them.

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26 minutes ago, Dave Pumphrey said:

These are max loads for given wire size, so the fuse protects the wire.

You would fuse according to the max maps that will be drawn from the circuit. 

 

Yes, that was 14 gauge because it was carrying the load of the headlights, this is the problem. 

Now it is only triggering the relay, a very small load.

18 gauge wire, 1or 2 amp fuse if you want one, really not needed.

Same for the ground side of the coil, 18 is fine.

A 10 gauge power to relay is a bit overkill, 12 would be plenty.

I would use the 12 to the headlights if you are running new wire to them.

Ok thanks. I'll probably run new wire to the headlights later when I do a headlight upgrade.

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2 hours ago, rcl285 said:

here is the VIP troubleshooting manual that contains schematics. 

Dick Lucas,  '04 Imperial

Troubleshoot VIP Wheel.pdf 330.97 kB · 5 downloads

Thanks Dick! I hadn't added that one to my library yet!

6 hours ago, rcl285 said:

This is a very simple solution to a design problem with the SmartWheel controller, but you lose the ability to flash your headlights with the button on the steering wheel.  The full headlight and current is routed through the controller through J11 pin 6 and J12 pin 1 or pin 2.  The flashing of the headlights is controlled by a module on the controller that operates a dual 25 amp relay,  I would suspect that the connectors that are most prone to failure Re the J11 pin 1 and J 12 pin 1.  J12 pin 2 only carries current when the headlights are flAshed on  during daylight for a short time.  I don’t know how valuable the ability to flash the headlights is important to most people is.  It is something which should be decided to each operator.  From the schematic I have, it appears that the headlight flashing is the only function that you lose by your modification.  Can you confirm?

i searched for the VIP troubleshooting guide but didn’t find it on line.  If anybody would like to have it, I’ll post it when I get to my desktop computer where it is stored.

By the way, on many motorhomes, the headlight wiring is marginal and has significant voltage drops which affect the brightness.  

Dick L  ‘04 Imperial

 


 

Hi Dick, you are correct. This solution does take away the headlight flash from the steering wheel.

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By the way, if you can catch the “toasted connectors” before they fail completely, you can take the headlight current off the SmartWheel controller using the technique described in danielsternlighting.com which uses two relays and upgrades the headlight wiring to minimize the voltage drops.  It reduces the current through those connectors to 100mA or so needed to drive the relays.  I had added this mod to a prior coach and it really helped the illumination. That was on a Freightliner chassis Endeavor and the headlight harness was maybe 10 feet long, all coiled up.  That chassis was an “ off the shelf” unit designed to be used in many applications and had enough wiring length to handle any situations.  My present coach had toasted connectors, but even though the headlights were not working, there was still enough conductivity to operate the relays used in the Daniel Stern mod.  I still have the ability to flash the headlights.  That was in 2013 and nearly 40K miles ago.

 

Dick L ‘O4Imperiad

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2 hours ago, rcl285 said:

By the way, if you can catch the “toasted connectors” before they fail completely, you can take the headlight current off the SmartWheel controller using the technique described in danielsternlighting.com which uses two relays and upgrades the headlight wiring to minimize the voltage drops.  It reduces the current through those connectors to 100mA or so needed to drive the relays.  I had added this mod to a prior coach and it really helped the illumination. That was on a Freightliner chassis Endeavor and the headlight harness was maybe 10 feet long, all coiled up.  That chassis was an “ off the shelf” unit designed to be used in many applications and had enough wiring length to handle any situations.  My present coach had toasted connectors, but even though the headlights were not working, there was still enough conductivity to operate the relays used in the Daniel Stern mod.  I still have the ability to flash the headlights.  That was in 2013 and nearly 40K miles ago.

 

Dick L ‘O4Imperiad

Excellent! I’ll check that out. Thank you!

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  • 2 weeks later...

I wanted to update the headlight problem I was having.  Thanks to Moe M and Rick P for their guidance on separating the headlights with a relay.  I now have working headlights!  It is very reassuring to have this kind of information and exchange of ideas to get us through these repairs.  I would have gotten to the headlight situation sooner, but my wife let me know the Samsung fridge would be done first.  Also many thanks to all those who shared their fridge change-outs and details on the how to's.  Thanks all!

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56 minutes ago, StephenW said:

I wanted to update the headlight problem I was having.  Thanks to Moe M and Rick P for their guidance on separating the headlights with a relay.  I now have working headlights!  It is very reassuring to have this kind of information and exchange of ideas to get us through these repairs.  I would have gotten to the headlight situation sooner, but my wife let me know the Samsung fridge would be done first.  Also many thanks to all those who shared their fridge change-outs and details on the how to's.  Thanks all!

Great! I'm glad it all worked out for you!

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