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Wiring the dash switch for Blue Sea ACR


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I installed my Blue Sea ML-ACR several months ago and have been very pleased with the resulting operation. My coach was not charging the chassis batteries while on shore power or house from the engine alternator. I had put off installing the BS supplied dash switch as just using the combine function a few times when starting in the cold was all I thought I really had to have. I installed two 3/4” PVC SCH 40 pipe runners thru the chassis crossmember holes when I did my FASS install to have a conduit for the new return hose. I pulled a heavy duty trailer 4 wire flat bundle from the Rear Run Panel into the Front Run Panel and then up to the side console.

A few days ago I had the dash out to see if I could get my trans temp gage to work and the switch is right there so a new project got started.

The exiting two position momentary ON switch has a CARLING VCH-01 8 style Terminal Connector Switch Base plugged into the the back. There are four female connectors plugged into the terminal base.

Double wire red for existing switch illumination, internal light power from headlight switch

Double wire white for ground used on above light

Single violet wire on terminal 2 - power from fuse 56 in FRP (pretty sure on the fuse number)

Single Violet wire on terminal 1 - switched power going to originally a Big Boy relay, now to the ACR

There are a couple of different wiring diagrams for the ACR and switch. I would suggest looking very closely for the one with a note that states the upper and lower LEDs in the ACR switch are connected together and will both be on or off as that helped me understand the wiring.

I used a thin flat screw driver to push in the tabs on the connectors in the terminal base and removed the four female connectors.   I had a few non-insulated female spade connectors left over from another project. I then made up a new 8” long jumper with a female connect on one end, a matching male spade connector on the other end and cut the wire in half to allow both wires to go into one female connector.  The female connectors on this jumper were plugged into the terminal base to attach to terminals 3 & 7 on the BS ACR wiring diagram. The wire previously connected to Terminal 2 (power from the fuse block) was attached to the male spade of this jumper to provide fused power to terminals 3 & 7.

On my original switch, the wire going to the Big Boy/ACR relay was on terminal 1, I moved it to terminal 2 of the connector base. This is connected from the switch to the ACR relay. A female connector was added to the new yellow wire and plugged into terminal 7.

The original ground white wire that was on terminal 7 was moved to terminal 1. When in the DO NOT COMBINE position of the switch,  it grounds the ACR to keep the relay from pulling in and combining the battery banks. I originally thought this was going to have to be a new wire.

The original red connector/headlight switched light power is not required for the BS ACR switch so I slide heat shrink over it. Heat shrink also insulated the violet wire power going to the jumper.

Not counting the jumper as a “pulled wire”, the only new pulled wire was the yellow from the ACR up to the new dash switch.

I thought I had taken a picture with the jumper wire between 3 & 8 in place. I could not find it. In the picture of the switch with the wires attached, the connectors are slide on the actual terminals of the BS ACR switch, not in the terminal base. The red alligator clip wire is jumping power from term 3 up to term 8. The bottom violet wire with electrical tape wrapped around it is the power wire from the fuse block.

The other picture shows how the little tab had to be flattened against the connector (red wire) so it could be pulled out the back of the terminal base.  White wire connector is were I pushed the tab back out so it would lock in. The connector seem to be available on Amazon, Baomain 1/4 inch (6.3mm) Female Spade Quick Splice Crimp Terminals, (link was really long). I may order a package, would never use 100 but for $7 they would be handy to have.

I ohmed the switch in its three positions b4 connecting wires. In the combined, rocked up position, terminals 3 & 2 are connected, sending power to the ACR from terminal 1 thru terminal 2. In the center position, both sides of the switch are open. When rocked to the DO NOT CONNECT position, terminal 2 is connected to terminal 1 which takes the relay to ground. The other observation is that terminal 7, the new yellow wire is grounding the LEDs within the switch. Any time the ACR is connecting the two battery banks, the yellow wire must be going to ground to illuminate the LEDs. Charging house bank on shore power with the ACR combined has the LEDs in the switch on.

Half way thru this project, I was not understanding what was going on. I almost just returned the switch back to the original state and lived with only the momentary switch. As I stated earlier that learning the top and bottom LED did not give a separate status for the switch helped me to understand what was going on and finish up the wiring. I was over thinking the project.

Hope this helps someone else taking this on.

HRS BS ACR switch.jpg

HRS female connector tab.jpg

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