1st Gen MK 2 CMU unit modifications for HID or LED headlight and LED bulbs

[lonestarmedic]

One of the things that has always seemed to be missing are pictures of the CMU circuit board on the 1986 and up and/or Royale circuit boards. So when I jumped the 4 reed switches on the board I snapped a couple pictures. All the reed switches go to a common ground so I just made a small harness and sent them to 1 ground point. It saved soldering on both ends of the reeds.

 

The reed switches operate by the copper coils creating an electromagnetic field that trips the reed module going through their coil centers. So, when jumpering you are after the center connectors, not the coils.

 

I did not bother chasing which one did the brakes, turn signals, running lights or headlight. I intend to install some LED lighting in the other circuits so I just did them all. My main goal was the headlight indicator. But, why go back in a second time?

 

Feel free to use these and copy. If someone knows which reed runs which circuit by all means label them. The reed switches are marked on the board as RS1, RS2, RS3, and RS4.

 

After I soldered the wires, I coated the solder joints with black liquid electrical tape to reseal them. The multi wire joint was protected by taking a piece of clear fuel line and sliding it over. I filled the inside of the piece of fuel line with some clear RTV sealer.

 

[Prairiehammer]

One of the things that has always seemed to be missing are pictures of the CMU circuit board on the 1986 and up and/or Royale circuit boards. If someone knows which reed runs which circuit by all means label them.

 

 

[ATTACH=CONFIG]100817[/ATTACH][ATTACH=CONFIG]100818[/ATTACH]

[ATTACH=CONFIG]100819[/ATTACH][ATTACH=CONFIG]100820[/ATTACH]

[ATTACH=CONFIG]100821[/ATTACH][ATTACH=CONFIG]100822[/ATTACH]

[ATTACH=CONFIG]100823[/ATTACH][ATTACH=CONFIG]100824[/ATTACH]

 

[lonestarmedic]

Very cool Prairiehammer. I will grab your pictures and store them with mine. Sometimes difficult to find. Toms of the earlier ones shown. Thanks so much for the addition.

[syscrusher]

Those diodes look similar to the failure prone ones used on the Mk1 TCIs. I wonder if they should be replaced too?

[Flyinfool]

Those diodes look similar to the failure prone ones used on the Mk1 TCIs. I wonder if they should be replaced too?

 

The TCI diodes that fail are not failing electrically, it is a mechanical failure due to corrosion from getting wet. The ones in the CMU are well conformal coated to keep them dry and I have never seen or heard of a CMU with signs that water had gotten in it to start a problem. There is also no track record of the diodes in the CMU failing for any reason. I would/did leave them alone.

[OutKast]

i am not clear on the location of the common ground.??

[lonestarmedic]

OutKast- If you look at the CMU you will see that one side of each reed switch is soldered to a common board trace. I chose to do my modifications from the component side of the board. If you go from the back side, just use some 18-20 gauge wire and solder to the individual spots.

 

All of the reed switches are connected to ground on one side to keep the module indicators turned off. I chose the common idea to reduce my soldering.

 

JB

[lonestarmedic]

Syscrusher, I cannot recall coming across a CMU with bad diodes. Maybe because the are not stressed with current and/or heat like the TCI?

 

JB

[phonetrouble]

it looks like you just strapped out the reed relays, and did not put any grounds in place. Is that correct?

[Flyinfool]

That is correct, you are just jumping all of the reed switches so that the computer thinks they are always closed.