AVCC Small Issue

[rcsnclh]

Just installed the AVCC per the many posts on this and other sites and everything worked perfectly. Almost. Unit doesnt disengage when I use the rear brake. I used the Yellow/brown wire going to the back of the bike and when I tested it with the front brake, saw the needed voltage signal. Didnt even think that applying the rear brake wouldnt impose the same voltage on this wire. My simple mind sees a continuous circuit through the brake light that would let the voltage pass through and energize this wire when I step on the rear brake. Evidently not. Before I dig in too deep to try and find the right/other wire to connect to, anyone have any tips for making this last little bit work? 2004 ABS model. Thanks !

 

[Twigg]

First ... Do you have LED brake lights?

The wire you connected to is the hot side of the brakes (the correct wire). The Cruise Control works by sensing a "drop to ground". That is, when you apply the brakes the CC detects a drop in the voltage on that wire as the bulbs illuminate, and it disengages. LED bulbs do not pull the voltage down low enough.

If you have tapped into the right wire (Checked by sensing 12V with ignition on, and probably about 7V when you apply the brakes) then you probably simply have a minor wiring or connection issue.

You can check it by probing the "brake sensing wire" that goes to the AVCC unit. That should also see the same voltage change.

 

[rcsnclh]

Thanks Twigg. Lights are NOT LED. Should have mentioned that AVCC disengages when I tap the front brakes. And as I understood it, the AVCC disconnects by "sensing" voltage, not by a drop. Hence the need for a relay if LED lights were installed. Maybe I have it backward? When I was checking voltage on installation, there was minimal voltage on the wire when keyed on, and then 12 V when I applied the front brake lever.

 

[mcatrophy]

Stupid question, does operating your rear brake light your brake light?

The (UK) wiring diagram that I have for the 2004 ABS shows both switches in parallel, either should put the same 12v on the brake light (and on your sense wire).

Maybe you have a switch/wiring issue on your rear switch.

 

[rcsnclh]

Not stupid at all, Mcatrophy. I checked and either lever (front or rear), activates the brake. Next check is to unwrap the soldered connection and see if there is 12v when I step on the rear brake. Given my symptoms, I would thuibnk not, but then agian I was the guy asleep in the back of the room during electric circuit basics

 

[Twigg]

Not stupid at all, Mcatrophy. I checked and either lever (front or rear), activates the brake. Next check is to unwrap the soldered connection and see if there is 12v when I step on the rear brake. Given my symptoms, I would thuibnk not, but then agian I was the guy asleep in the back of the room during electric circuit basics

Brake light circuits are the other way round.

They should be hot on the bulb side of the switch, and ground after. The switches simply switch to ground.

Your AVCC expects to see 12V in the brake sensor wire, at all times. It is waiting for a voltage drop when you hit the brakes.

 

[wfooshee]

Yeah, the failure people get with LED lights is when the voltage on the line with brake lights off is not 0 or VERY close to 0. If the cruise sets, that's not your problem.

The issue is that the front lever works but not the back. There's not an electrical issue with the connection because the front lever works. The only thing I can see causing this is no brake lights from the rear pedal.

The switches are in parallel. They have 12 volts from the signalling fuse on one side, and the brake light bulbs on the other side, with ground beyond the brake light bulb. They are not separate circuits,the 12V wire on one side of the brake light is the same wire, and the switched wire on the other side of the switches, going to the brake lights, is the same wire.

The only way the front can work the disengage and the rear not, is for the rear to not light the brake lights.

I do know that on my bike, I can get a very slight rear brake action BEFORE the brake lights illuminate. If using the rear only, I have to give it a firmer push to actually get brake lights. It shouldn't be that way, but it is. Since I primarily brake with the front, i don't really care. And I CAN disengage my AVCC with the rear, but not just by tapping the lever, I have to actually get some braking action on. At the front, a small tap is enough for that switch.

And the above post is incorrect. The AVCC connects to BOTH sides of the brake light switch. It gets its 12 volts from the hot side of the switch through its red wire (although some people connect the red wire elsewhere, to any switched 12V wire, which is fine, but putting it on the hot side of the brake light circuit ensures that the cruise won't engage if your brake light circuit is dead for some reason.) The purple wire is looking for non-zero volts to disengage.

From the AVCC manual:

 

[mcatrophy]

...Brake light circuits are the other way round.

They should be hot on the bulb side of the switch, and ground after. The switches simply switch to ground.

....

Not according to the diagrams I have. ALL FJR variants use a combined stop/tail lamp, the "common" connection to ground.
GenI bikes use simple switches in parallel, wired one side to fused 12v, the other side to the stop light bulbs.

GenII and GenIII use a system of relays, but the final result is the same, 12 volts switched to the stop bulbs, the "common" from the bulbs taken to 0v.

In all cases the AVCC sense line should be taken from the feed to the bulbs, 12volts = brake(s) applied.

[Edit] I don't see a "yellow/brown" wire, only a yellow wire to the brake lights. So my diagrams may be wrong, but I still don't believe they use a grounding switch circuit. [/edit]

 

[Twigg]

Correction accepted.

 

[lnewlf]

or, put differently, if you are using a relay....

when either brakes is applied current energizes the relay pull down coil breaking the CC's ground connection causing it to disengage....

 

[wfooshee]

Huh????

The purpose of a relay on bikes with LEDs in the brake light system is to separate the brake light circuit from the purple wire until the brakes are applied, at which time 12V is applied to the purple wire.

LED systems seem to keep 4 to 6 volts floating on that line, preventing the cruise from engaging. The relay disconnects the purple wire until brakes are actually applied.

Doesn't mean anything for the OP, though, he's got no LED systems.

And as I said before, it's NOT an electrical issue or the front brakes wouldn't disengage the cruise. I think it's a matter of the switch on the rear pedal engaging "late" rather than as soon as the pedal moves.

 

[lnewlf]

Meebee it's different with my Global Cruise [Rosta]....but the relay is used to break the CC's ground connection when energized by the brake wire....I followed the instructions that came with the unit and it works perfectly...I am not supplying 12 V to the purple wire...and yes, the relay does separate the brake circuit from the CC.

 

[wfooshee]

The main ground for the unit? Wouldn't that simply turn it off? Wouldn't it forget your speed and be unable to resume?