Lean angle cut off switch......now no dash screen, and no start?

[mattster344]

Good afternoon, 

Had my 2003 apart this winter to do the valves (clearance and head cleaning, re-lapped etc)......

Got it back together and on the first start up, I had some challenges keeping it running....it would just die for no apparent reason. I discovered the lean angle cut off switch (LACO) under the seat was the culprit as I could tap it/wiggle it, and for some reason the bike would run again (connector was cleaned etc). Rode it today as I thought the cleaning had it fixed and it happened again (thankfully not far from the house so got it home). 

However, not only is the lean angle switch bad, but I now have no dash screen. Perhaps I tapped the LACO a bit too hard and something shorted? I checked fuses to no avail. 

Has this potentially fried my ECU as well? 

Anyone with a similar experience with this switch and/or advice?

Thanks!
Matt

 

[mattster344]

Update.....took the switch apart and there is a small circuit board inside, and one of the pins was loose.  This would certainly explain the intermittency of its operation and how the engine would fire upon wiggling/tapping it, but not the loss of my dash screen. There is now no "needle sweep" upon turning the key or fuel pump whirring (running lights, neutral light operate however). That said, in attempting diagnostics, I have a feeling when I was fiddling with the switch and testing the continuity of the female plug I may have inadvertently jumped two contacts together somehow. The question becomes would this have fried the ECU and the dash readout? 

I have ordered a new lean angle switch and am looking for a used ECU online. I believe any Gen 1 should work (2003-2005). 

M

 

[mcatrophy]

am looking for a used ECU online.

Be careful. Needle sweep etc is controlled by the Meter Unit, not the ECU, the ECU controls the engine and is the box under the seat. 

 

[mattster344]

OK then.......the meter unit being the LCD display on my dash then? That makes sense but in looking at the wiring schematic it appears two wires route directly into the ECU so I made an assumption.....more than likely incorrectly. I pulled the "back up" fuse and on reinsertion the gauges "sweep" but still no joy on the display, nor upon turning the key. 

 

[escapefjrtist]

Ignition switch? IIRC there Are two sets of contacts for the various functions, at least on the latter year models. 

~G

 

[RossKean]

I doubt that your problem is either the lean angle or the ECU.  Assuming a fuse hasn't blown somewhere, I would agree with escapefjrtist that the ignition switch is highly suspect.

This was a very common problem with early Gen II but a fair number of Gen I complaints as well.

 

[mattster344]

I will certainly check the ignition switch again, but I did have the switch malfunction several years ago. The result was zero activity with lights, dash, FI rail etc....A wire had pulled loose so I re-soldered it. I could wiggle the cable out of the switch to replicate the symptom......this time no effect. Right now turning the key will still activate the lights on the dash and running lights, but no " instrument sweep", LED display or fuel pump whirring. 

Initially the bike started fine and would just stop (like I had flipped the kill switch). After checking connections/fuses/sensors I discovered that when I wiggled the LACO it would trigger the normal function of the fuel pump etc and the bike would start (while the key was on). So initially I unbolted it to see if I could manipulate it to replicate the symptom. Lo and behold when I would twist the sensor, tap it, wiggle it (not rotate it on its side though) it would cause the bike to shut off. It would then take a bit more wiggling/tapping to then activate the fuel pump etc. for a restart. 

I then unplugged it to clean it out again and I thought it was ok (mind you I didn't play around with it). Went for a ride and it died 2 K down the road. I would take off the seat, tap it firmly with the key "on" and the fuel pump would come alive and it would start. 

Then I took another look at the switch and found a bad solder joint in the circuit board (pin had separated from the solder), which seemed to me to explain the symptoms. I then checked the wiring continuity on the female plug..... It was after this that I then noticed the LED screen would not come on, along with an absence of the Fuel pump whir and "instrument sweep" (although the sweep does occur when I pull the back up fuse, or when unplug the back of the dash panel and reinsert....but not the fuel pump). That's what got me thinking I accidentally shorted it (crossed the probes) and I initially thought ECU but mcatrophy made me think its the meter unit in the LED display itself? 

In any event I have another LACO switch coming and am thinking I should try to find a used gauge cluster instead of the ECU. I am at a bit of a loss otherwise on this. If the gauge cluster doesn't do it I will try the ECU.....there are several on Ebay.

 

[huron52]

Take it to Ray ….He lives just down the road from you, doesn't he?      He likes a good challenge

 

[mattster344]

Take it to Ray ….He lives just down the road from you, doesn't he?      He likes a good challenge

I believe so yes......and no doubt he would be up for the challenge, but not sure I would want to impose this one upon him. 

UPDATE:

I received another LACO sensor and a used gauge cluster. I was hoping the cluster, which houses the meter assembly, would do the trick. So after checking the continuity of every fuse and relay...... and checking the condition of every connection (I even removed the ignition switch and checked that) I installed the gauges and sensor.......no change whatsoever. Behaves the exact same, no LCD display, no gauge sweep or FI rail whir. Given all wires from the LACO sensor feed through the ECU that has to be my last option, and I inadvertently fried something when I must have shorted the contacts together on the plug to the LACO sensor......hopefully a replacement ECU will work.

That said, the one I have coming is from a 2004 model, but I understand the Gen 1 models are basically the same, so it should work. We will see.......

M 

 

[mattster344]

UPDATE:

This is rather embarrassing but it certainly was a learning experience. Turns out the issue was a blown diode and ignition fuse. While I did check the fuse previously and it looked ok, to my surprise it had blown in a way that didn't appear obvious when viewed straight on......certainly should have checked it for continuity because it took me a while to discover that when I turned the fuse in my hand, it had separated perpendicular which is why it appeared fine when I looked straight on....lesson learned.

As far as the diode....it was the little one that you find off the ignition relay beside the battery. It allows power to flow between the kill switch, the starter relay handling the fuel pump and the ignition relay module that sits under the seat (which was my third diagnosis after the replacement dash and ECU didn't change a thing.....and another one of those also made no change).

The FSM made no mention of this particular diode in diagnosing starting issues, it only refers to the process of checking the ignition relay module diode (the one under the seat). This diode doesn't even show up in a parts fiche. 

So after reading the wiring diagram about a million times, and locating this diode, I pulled it out to discover it had no continuity in either direction (should have allowed flow one way at least), so I surmised that in shorting out the connection at the LACO sensor, it blew the diode and the fuse because the side I shorted out had a direct connection to this diode. Makes sense given the purpose of the LACO is to kill the motor. Anyways, popped in a new diode ($5) and fuse and it started right up.....however after doing this several times, I would press the start switch and instead of the starter motor turning over, all I would hear is the fuel pump engaging. So I replaced the ignition relay (under the seat) with the new one I had previously ordered and it solved the problem.

I would have never thought that shorting a connection on the LACO sensor would create this kind of headache. So I now have a spare dash cluster and ECU.........sobering lesson for sure but a happy ending. 

 

[mcatrophy]

diode, I pulled it out to discover it had no continuity in either direction

Does the meter you used to check continuity have a specific diode setting? A simple ohms range, or a normal continuity range (with audible beep) , won't normally show conduction even in the forward direction.  

 

[mattster344]

Does the meter you used to check continuity have a specific diode setting? A simple ohms range, or a normal continuity range (with audible beep) , won't normally show conduction even in the forward direction.  

Yep, the meter I have has a diode setting with a max of 2.8 volts across the connection. I agree, I don't think the normal ohms range "beep" setting would show the conduction. That said, I never actually tried it on that setting so now I am curious.