Subject: Honda OEM Heated Grips
I went from completely dead to fully functional heated grips.
If you are interested…
2006 ST-1300 “Deluxe”, 170.000kms ish.
This is winter, yes I am in Montreal, Canada, and it is the best time to do major maintenance on the bike..
This year, one of the subjects was the unfunctional heated grips.
Symptom
In the last few years I noticed that the grips didn’t work well. Couldn’t set the maximum without the controller power indicators starting to flash. (First symptom).
That was followed by a continuous drop in heat capability. Down to nonfunctional. In other word dead!
Analysis
Since I had to remove the plastic for other maintenances, it was time to handle this problem.
BTW, I am a seasoned retired power electronic designer. This is my domain! And I have time to “play”
Analysis
First thing first: Unmount the controller from the fairing and test it on the bench with a simulated load (a 12V bulb) Works absolutely fine. Cut-off voltage is around 12.7V. The level where the controller is set to stop working. This is important to know.
Cut-off is nice and clean, no flashing.
Right there, it confirms my first impression that, for some reason, there are increasing voltage drops during operation, on the bike.
Took a scope to look at the operation (the grip controller is a PWM controller) and monitored the voltage directly across the controller power input and ground, on the bike, during operation. And yes, there it is, a total of around 1.2V drops at the controller when ON.
There is almost the same amount of drop on the plus side and the minus side, for a total of 1.2V
Note the test was supported by a battery maintainer capable of simulating a charging system in operation. Test voltage is maintained at 13.7 volts at the battery terminal. (Could’n run the bike in my garage, door closed. Hey, it is winter…)
Corrective actions
This is the bad part. There are so many connectors and other electrical connections that it is almost impossible to pinpoint the failure location. The connectors directly involved (located in front of the frame, near the fork) were visually inspected. Nothing really apparent. No corrosion anywhere.
I also notice that, when the Emergency Flashers are on, there is a similar drop, at the Grip’s controller. Common circuit…
A very quick check on the fuse blocks revealed nothing.
More you check, the scarier it becomes. Where is the problem, if there is one?
Design flaw?
Wiring Diagram
After spending almost 3 days deciphering the wiring diagram and making a correlation between the 2003 diagram and the actual 2006 version (they are not the same, but similar enough to get a minimal understanding.) I decided to bypass the problem.
At least for the heated grips.
I didn’t want to create more problems by dismantling too many connectors/harnesses if it is unnecessary.
Afterall, this is an 18 year old bike…
Solution
Bypass the whole circuit and power the heated grips controller directly from the battery terminal for the + side and directly to the frame for the - side, close to the grips controller.
Of course, the new circuit must be controlled by the ignition key/main relay. And fully protected. I have also checked and confirmed the charging system before winter storage. A nice 13.7V
End
Works perfectly fine. Full power and kicks off à 12.7V (Vbat). No flashing. Almost too hot!!
And, why not? I also added a voltmeter, and a double USB charger connected to the ACC circuit.
If interested, the improved diagram is attached, including in the diagram some valuables notes.
