GL1200 Aspencade Ignition Switch Voltage loss


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SlowTyper
Posts: 59
Joined: Fri Jun 25, 2010 7:37 am
Location: Pierre, SD
Motorcycle: 1985 GL1200 Aspencade

GL1200 Aspencade Ignition Switch Voltage loss

Postby SlowTyper » Thu Sep 04, 2014 7:31 pm



This post covers my diagnosis/repair of the ignition switch on my ’85 Aspencade. I am sharing this in hopes that others may benefit from the info – I know I have certainly been helped by other’s posts!

My first GL1200 had the classic stator failure, and at that time I learned all about the GL1200’s electrical issues. Consequently, I have kept a close eye on the voltage displayed on my GPS [iWAY 600c] that I installed on my second GL1200 – a bike I plan to keep for a while because it has been heavily customized.

My sagging voltage indications were initially subtle and infrequent. But over time, they became more pronounced. Since the stator connector near the battery has been cut out and the yellow wires soldered, I knew my problem had to be elsewhere. I speculated that the next most likely culprit had to be the connector for the voltage regulator. So I soldered those connections too. But alas, that didn’t fix the occasional voltage droop!

So I dug out my multi-meter and began troubleshooting rather than guessing (my next guess was the 4-pin plug on top of the starter solenoid to the right of the battery). Unfortunately, my efforts to diagnosis the problem were aggravated by the fact the voltage drop was intermittent and relatively infrequent. However, I did notice that there was a measurable voltage drop across the ignition switch; the amount of that voltage drop varied (0.1 – 0.4volts) as I wiggled the key.

The connector for the ignition switch is readily accessible. It is inside the false fuel tank, on the right side near the front. Getting the ignition switch out of the bike was a hassle – the two mounting bolts are almost totally blocked by the fairing and a metal air line that runs between the front shocks.

Once the switch is out of the bike, it opens up by removing a cover held by three screws and two tabs:
Switch Cover
Switch Cover
Wires to Switch
Wires to Switch
Spring Loaded Key Position Detent Balls
Spring Loaded Key Position Detent Balls


I was relieved to see there were no melted plastic parts, fried contacts, nor weaken springs. There was some corrosion, but it was easily cleaned up.

Before cleaning:
Dirty Contacts
Dirty Contacts
Springs
Springs
Dirty Connection Area  (notice the dimples!)
Dirty Connection Area (notice the dimples!)


After cleaning and wire brushing:
Cleaned Contacts
Cleaned Contacts
Cleaned Connection Area
Cleaned Connection Area


To reduce the load on the ignition switch, and hopefully make it more reliable, I added two 30Amp “horn relays”; one to power the Ignition bus, and the other to power the Accessory bus. I inserted them just downstream of the ignition switch connector inside the false fuel tank. FYI, the Red wire is battery power; the Green /w Blk stripe wire is Accessory power; the Black wire is Ignition power. The other wires power the Radiator Fan and the Taillights – I did not mess with them since they do not carry as much current (yes, I’ve added a few accessories to the bike <grin>).

For good measure, I also ran a jumper wire between the Battery lead going to the ignition switch and the Battery lead going to the voltage regulator. I figured this would minimize the voltage drop on both of those wires since the current flows in opposite directions. After my modifications, the voltage drop on the ignition and accessory circuits (now powered through relays controlled by the key switch) does not exceed 0.1VDC.

For completeness, I should mention that some ignition bus power flows through the starter button on the right handlebar. Specifically, the lights get their power through the normally closed contact of this switch, which is why the lights go dark while starting the bike. Consequently, this is a potential failure point even though I have never read of it causing trouble.

Unfortunately, even though this project eliminated a voltage drop problem at the ignition switch – I still experienced significant voltage sags at times (most notably on the ride home from Sturgis). Hmm…. It turns out the stator appears to have an intermittent short between turns/windings (no shorts to ground yet) – however, that diagnosis is the subject for another post another day.



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