Lee H. Mann
Gone But Not Forgotten
I don’t know exactly where to post this and I searched TT for similar posts and found none.
This post has to do with an ECM failure on 2002-2005 FLH-FLT models.
Symptom:
My brother-in-law’s motorcycle (not trike) developed a small miss one day while riding. It then smoothed out and ran fine for another week or so. Next it developed a miss that was so bad he almost was unable to make it home. It shut down and he was unable to get it started again. Relying on cheaper-is-better he replaced the throttle position sensor, manifold pressure sensor, crank position sensor and it made no difference. He then replaced plug wires and plugs and it fired on the front cylinder only.
He didn’t realize at the time that the rear injector was sticking open spraying gas and it was later running out the tailpipe.
Diagnosis:
I looked at the bike and found that it was either a bad fuel injector or the ECM. I determined this by switching injectors and putting the supposed faulty injector to feed the front cylinder. I started the bike and the rear cylinder came to life but now the front cylinder was dead and throwing gas out of the front pipe. Voila, so I ordered 2 injectors from HD.
After installing the injectors I spun it over to dump the gas that was in the cylinders and replaced the plugs.
Injectors were just replaced and it still had a dead rear cylinder dumping raw gas into the exhaust. WTF !!!! I looked through the throttle plate and it looked like a shower room when I turned the key on. WTF !!!!!
The ECM:
Long story made short, it is the ECM. I still don’t know why it went from the rear injector to the front injector, but it did. I was told by a tech that you could replace the module with a good working module and the bike would start and then shut off without the mated sensor. I removed an ECM and Bank Angle Sensor from a 2003 FLHTCUI and installed it temporarily and the bike started like it had been running all day.
The 2002 and 2003 modules had different part numbers but would interchange if coupled with the mated Bank Angle Sensor.
Harley-Davidson in the infinite wisdom has been upgrading their ECM’s since day one. Every year and model are different but the latest and greatest offering from Harley-Davidson is a one size fits all. The new ECM is a blank platform that the dealer has to plug into and download upgraded and updated MAP information according to your specific VIN number, and then it has to be mated with your existing Bank Angle Sensor/Turn Signal Module/Security Module.
You cannot simply replace the module anymore, it has to be done through a Harley-Davidson Dealer.
I had found some used ECM's for $100.00 or less but I don’t want to chance being 150 miles from home and have that bargain ECM let me down. I hope this helps someone from making a costly mistake and dumb mistake.
This post has to do with an ECM failure on 2002-2005 FLH-FLT models.
Symptom:
My brother-in-law’s motorcycle (not trike) developed a small miss one day while riding. It then smoothed out and ran fine for another week or so. Next it developed a miss that was so bad he almost was unable to make it home. It shut down and he was unable to get it started again. Relying on cheaper-is-better he replaced the throttle position sensor, manifold pressure sensor, crank position sensor and it made no difference. He then replaced plug wires and plugs and it fired on the front cylinder only.
He didn’t realize at the time that the rear injector was sticking open spraying gas and it was later running out the tailpipe.
Diagnosis:
I looked at the bike and found that it was either a bad fuel injector or the ECM. I determined this by switching injectors and putting the supposed faulty injector to feed the front cylinder. I started the bike and the rear cylinder came to life but now the front cylinder was dead and throwing gas out of the front pipe. Voila, so I ordered 2 injectors from HD.
After installing the injectors I spun it over to dump the gas that was in the cylinders and replaced the plugs.
Injectors were just replaced and it still had a dead rear cylinder dumping raw gas into the exhaust. WTF !!!! I looked through the throttle plate and it looked like a shower room when I turned the key on. WTF !!!!!
The ECM:
Long story made short, it is the ECM. I still don’t know why it went from the rear injector to the front injector, but it did. I was told by a tech that you could replace the module with a good working module and the bike would start and then shut off without the mated sensor. I removed an ECM and Bank Angle Sensor from a 2003 FLHTCUI and installed it temporarily and the bike started like it had been running all day.
The 2002 and 2003 modules had different part numbers but would interchange if coupled with the mated Bank Angle Sensor.
Harley-Davidson in the infinite wisdom has been upgrading their ECM’s since day one. Every year and model are different but the latest and greatest offering from Harley-Davidson is a one size fits all. The new ECM is a blank platform that the dealer has to plug into and download upgraded and updated MAP information according to your specific VIN number, and then it has to be mated with your existing Bank Angle Sensor/Turn Signal Module/Security Module.
You cannot simply replace the module anymore, it has to be done through a Harley-Davidson Dealer.
I had found some used ECM's for $100.00 or less but I don’t want to chance being 150 miles from home and have that bargain ECM let me down. I hope this helps someone from making a costly mistake and dumb mistake.
