Code 81 - need some help in figuring out the circuit

[K-fab]

Hoping someone can help me out here.

I've searched for Code 81 and it pops up but the results are not quite what I'm after.

I need some help from an electrical guru.

I'd like to give a little background on my abilities, so anyone attempting to help me realizes I know what I'm doing, just stuck for the moment from a lack of hands on with a full system. I don't have a sled, just the engines and electrical systems.

I fully understand how the Yamaha system works (as in how the sensors convey their info back to the ECU and how it takes these inputs and activates the pertinent section). They system's really quite simple once you break it down into each component. Sensor & reactor, pretty much. Some sensors just flip on a light (high beams) some activate a relay (fan) some activate some sort of limp mode (EFI section, low press on oil, etc.).

I was able to take an RX1 system and install EFI from an R1 bike, Frankensteining the harnesses and making a system that worked beautifully.

I've taken two Phazer's powerplants and transplanted them into a couple of single seat off road race cars. Here's another build log. The last few pages are more pertinent to this post.

I've done four wire harnesses redos on these stadium cars. My first and third wire harnesses did not throw any codes. My second and fourth are throwing Code 81 - grip heat.

Now here's my issue: I've been able to strip about 40% of the Phazer's harness out. Things like the lights and radiator fan system have been put on their own circuit (rad is still controlled by the ECU). The gear selection system's been removed. The grip heat's been removed too - well, sort of.

Now, I see in the manual that the grip heater switch is used for diagnostics and code clearing. So I need a little info on how that circuit works.

First off, is grip heat always on? Is it only toggled between high and low? There are two control wires (white with red and white with blue as I recall). Each of these lines reports back to the ECU, which selects an appropriate output (low or high) and activates an appropriate relay.

With Code 81 showing up, it says it's either an open or short in the wire harness. - I know there is no short, but open? Does it look for an input? The switch circuit grounds the input (high or low selection) lead to activate. So is it telling me that there must be a selection wired? - and would this be what's considered open?

I had a response, in my build thread of read it on tty, you can use a resistor to mimic the heaters to clear the code. Think it was 100ohms. So, is the ECU seeing that there's no load on the output control lines from the ECU? If so, do I need to mimic the relay's control circuit with a resistor that's similar in resistance to the relay's coil?

If I were to ground out the input for the low heat selection (activate it) and then put a resistor in the output control's line, would this trick the ECU into thinking that there's a grip heater onboard and make Code 81 go away?

When the switch is used as a code clearing device, how do you go about it? I've read the service manual a couple of times, but I'm not quite sure I get what they mean?

So, any help that anyone might want to throw my way would be very appreciated.

Thanks in advance.

 

[Rockmeister]

Hi K-Fab!

Can help you with the code 81.
You need a dummy load resistor of approximately 10 ohms.
It will need to be at least 20W rated and may get HOT!
This will eliminate your code 81 problem.
(Assuming everything is wired correctly.)

Will send you my phone number in a PM & we can go over what you need.

Some additional info:

If you short the ECU output, it will also show up as a code 81.
The grips default to the last known heat setting.
If they were left in "off" position, they will power back up in "off" position.
(Would suggest setting them to "off" except to use the switches for clearing codes etc.)
The code 81 is a self-clearing code, meaning at re-start, if the condition causing the code is fixed, the code will self-clear.
(Sometimes it takes 1 or 2 re-starts.)
There is no relay in the grip warmer circuit.
The Grip warmers are variable from off, to 8 "on" levels.

Hope this helps!

Rock

PS Where are you in Ohio?
May be pretty close to you.

 

[K-fab]

THANK YOU!!!!

 

[K-fab]

It works beautifully!

I put a dual throw, momentary switch into the circuit and a test light on the output lead for resistance and to complete the circuit.

Right there on the dash, I could control my grip and throttle heat and watch the graphic go from low to high to off, one step at a time. The test light would get brighter with each change and then go off.

I was able to set both the heated pieces to off and no more codes! Was able to reset my second ECU too.

Thank you very much. Dilemma solved.