1100 RT Electrical Woes

[R6T5]

New member, first post -  Thanks in advance for any info.

 

I've been wrenching on Airheads for some time & recently found myself in possession of a '99 1100 RT. It has no spark and here is my situation: The tank is removed, fuel pump naturally unplugged, Hall Sensor unplugged and I find that there's no voltage from the red wire that powers the HES.

 

Side stand switch is ok, clutch/neutral switch functions, kill switch works and actually all lights, horn, power windshield work perfectly. All fuses and relays check out, the bike cranks but I have no voltage going TO the HES. Should I? Considering the bike is stripped, shouldn't there still be voltage from Motronic with the key on? 

 

Forgive me as I'm not familiar with Oilheads at all, but I have a feeling (with some help from your forum) I soon will be! (My original reason for stripping the bike was to replace the HES, but after some testing I find there's no voltage being supplied to it.)

[dp-R1100RT]

Seems like an honest question.  I'm new here too, so I will just suggest that you research what the HES requires (voltage/amperage.)   Maybe it does need to be running.  Does it have power when the starter is engaged?  If not, then try jumping power to it, and see if it runs.  The HES has known problems with shorting out due to wire insulator, and other issues.  A direct short may burn fuses immediately.

 

A running vehicle always makes for an easier diagnosis.  Not to be a know it all, but diagnosis is your key to being a mechanic vs a parts replacer.

 

It is like being a detective on a case - "just the facts ma'am."  You are working on 3 basic systems on modern vehicles:

1. Fuel

2. Spark (electronics)

3. mechanical problems.

 

Step 1: compression tests. (mechanical test)

Step 2: crank it and smell for fuel. (fuel test)

Step 3: crank it and check for spark. (electrical test)

 

If any of them fail, then you have narrowed the problem, and you (hopefully) won't be buying a new coil for a fuel problem.

 

 

Isolate, and eliminate prospective systems, before you start to narrow your focus, and eliminate specific parts within that particular system.

 

Test, test, test.  If you think that the coil is bad, then there is a procedure to test for that.  Always test a part before you replace it.

 

This is where I get off track, After 40 years as an auto mechanic, I can't even count the number of "basket cases" where people have replaced coils, fuel pumps, even entire fuel injection systems, when the problem was a jumped timing chain, or a crank position sensor.  They spent $100's of dollars replacing perfectly good parts, and they finally took it to a professional mechanic.  Follow the above rules, and if you are stumped - than ask for help right here, or else, bite the bullet, and take it to a professional.... it is much cheaper in the long run. lol

 

Let us know your results.  4-5 heads are always better than one, and someone much smarter than me will chime in at any minute.

 

Welcome to the forum new guy!  Yaaaa, I'm no longer the newest guy on the forum!

 

~dp

[dp-R1100RT]

follow...  I did it again..

[dirtrider]

14 hours ago, R6T5 said:

New member, first post -  Thanks in advance for any info.

 

I've been wrenching on Airheads for some time & recently found myself in possession of a '99 1100 RT. It has no spark and here is my situation: The tank is removed, fuel pump naturally unplugged, Hall Sensor unplugged and I find that there's no voltage from the red wire that powers the HES.

 

Side stand switch is ok, clutch/neutral switch functions, kill switch works and actually all lights, horn, power windshield work perfectly. All fuses and relays check out, the bike cranks but I have no voltage going TO the HES. Should I? Considering the bike is stripped, shouldn't there still be voltage from Motronic with the key on? 

 

Forgive me as I'm not familiar with Oilheads at all, but I have a feeling (with some help from your forum) I soon will be! (My original reason for stripping the bike was to replace the HES, but after some testing I find there's no voltage being supplied to it.)

 

Morning R6T5

 

You can push start these bikes so it doesn't have to be cranking on the starter  for the HES  to work.

 

You do need to see (key-on) 12v between the HES  high (red wire) & the HES low (brown wire) at the HES (main harness side)  pig  tail connector.

 

If no 12v at the HES red wire then start at fuse # 5 (don't just visually verify fuse #5 but use an ohmmeter to verify fuse #5 continuity, or use a DC voltmeter to verify 12v in & verify 12v out of #5 fuse. Or replace fuse #5.  (fuse 5  MUST be verified  to HAVE 12v to it, & be verified to be passing 12v through it, don't guess on this)

 

You also need to verify that you have key-on 12v into the Motronic from the (engine electronics relay) --  With side stand UP you need to see key-on 12v into the Motronic on the (green/black wire) going to pin #33. If no power on this wire then verify that the engine electronics relay is operating & that you have full time  B+ 12v going into engine electronics relay  on socket pin 1 (relay terminal 30)  & key-on 12v going into the relay on socket terminal 3 (relay term 86). 

 

The engine electronics relay won't energize without the side stand switch working correctly so (I know you said it is good)  but either by-pass that or at least make darn sure that it IS working correctly (this is a must before moving on).   

 

If you (or someone else) has been messing with the HES  with key-on, or the HES was shorted between certain wires due to moisture then there is a slight chance that the Motronic is locked out. Usually a fuse (5) removal for a few minutes will unlock it but in your case I would recommend  a full battery disconnect for about an hour just to be sure.

 

You (first) need to verify the (full time B+ 12v) & (ign-switch-on  B+ 12v)  into the Motronic before getting ahead of yourself. If those are not there then diagnose &  figure that part out first. 

 

Does the dash RID come on??? This can be a tell-tale to look for on basic ign-switch B+ 12v.  

 

If all the B+ & ign-on 12v inputs test out OK then we will probably have to go after the lows (grounds) -- this will have to be in it's own stand alone reply though.

 

Give us some more history on how/when your current problem started (like was it running then quit, or stored for a long period & wouldn't start, or ????????).

 

Sometimes if we have more history on the bike & exactly when  the problem appeared we can get you closer to where to start looking.

 

Last thing: I worked with a rider a while back (long diagnostic process) & through a long series of eliminations & testing  it turned out to have a failed Motronic. Best we could figure that was caused by a shorted HES feeding 12v back into the Motronic on an incorrect circuit. (not to get ahead here, just something to keep in mind)

 

 

 

 

[R6T5]

Thank you. I appreciate this advice because that tells me which pins/wire colors/relays to chase after at the Motronic connector. As for history - the bike was sold dirt cheap with 38,000 miles on the clock because of the fact that it was not running. The PO told my buddy that it had no spark and instead of spending money on it, he bought another bike. Well . . .

 

It wound up in my garage where I verified that indeed it had no spark. My first thought was, GREAT! "I'll replace the HES & be off and running!" I removed the tank and upon checking for B+ at the harness, found that the PO had spliced the red wire and ran a jumper to a hot fuse, trying to power the HES. I verified voltage and ground and my next thought was -  bad Motronic. 

 

I checked the side stand, neutral, clutch switches. Everything electrical seems to work including RID, fuel gauge, headlight, tail & stop lamps, just no spark. I can't verify that the fuel pump actually ran with key on because I'm not familiar with how they sound, but that can be sorted out later, once I get the plugs to fire. On the up side, I have another 1100RT that is known to run (with bad final drive) that I could pull parts from, such as Motronic, coil, etc. 

 

As per your advice, I'll check for B+ and ground going to the Motronic & it's relay, pull the fuse (although the battery has been dead for months & just now replaced), try to reset and if all else fails I can install my spare Motronic. My first step was to join a forum and ask questions, because as you noted, I don't wanna be that guy who throws parts at a machine. ;-)

[dirtrider]

24 minutes ago, R6T5 said:

Thank you. I appreciate this advice because that tells me which pins/wire colors/relays to chase after at the Motronic connector. As for history - the bike was sold dirt cheap with 38,000 miles on the clock because of the fact that it was not running. The PO told my buddy that it had no spark and instead of spending money on it, he bought another bike. Well . . .

 

It wound up in my garage where I verified that indeed it had no spark. My first thought was, GREAT! "I'll replace the HES & be off and running!" I removed the tank and upon checking for B+ at the harness, found that the PO had spliced the red wire and ran a jumper to a hot fuse, trying to power the HES. I verified voltage and ground and my next thought was -  bad Motronic. 

 

I checked the side stand, neutral, clutch switches. Everything electrical on the bike works well enough to pass State inspection, just no spark. I can't verify that the fuel pump actually ran with key on because I'm not familiar with how they sound, but that can be sorted out later, once I get the plugs to fire. On the up side, I have another 1100RT that is known to run (with bad final drive) that I could pull parts from, such as Motronic, coil, etc. 

 

As per your advice, I'll check for B+ and ground going to the Motronic & it's relay, pull the fuse (although the battery has been dead for months & just now replaced), try to reset and if all else fails I can install my spare Motronic. My first step was to join a forum and ask questions, because as you noted, I don't wanna be that guy who throws parts at a machine. ;-)

 

Morning R6T5

 

While you are checking 12v inputs to the Motronic be sure to verify that you have full time 12v on the large red wire going to pin #15 of the Motronic connector (large red wire is a stand-out so easy to spot)

 

It sounds like you have a path to follow, if you get to something that you don't understand (or need defined)  just do a follow up post & we'll talk you through it.

 

On the fuel pump running check (when you get that far)-- At first key-on you ONLY get about 2 seconds of fuel pump run then it shuts down (to prime the fuel rail), then the pump won't run again UNTIL the engine is actually cranking (it  gets that cranking signal from the HES, to the Motronic, to the fuel pump relay).

 

You can also use this trait as a sort of poor mans HES test as with the key on you should be able to (slowly)  turn the front belt pulley bolt & hear the fuel pump start as the HES triggers.