ECM issue

[Lee H. Mann]

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.

[Bikerbozo]

Did any error codes come up on display?

[Lee H. Mann]

Error Codes:
Every time he had an engine light come up he would erase the codes so he didn't know which ones were being set off. Since he had no codes to refer to he was listening to everyone who was replacing the cheap parts first. I sent him a step by step on downloading the codes but he couldn't grasp it. When I got it there were no codes stored.

[1dn5up]

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.

Thank You

[Gorilla]

I replaced the ECM on my 2002 with one off Ebay that had the same part number and the bike ran fine. I don't know if you can do it on newer then that year.

[Lee H. Mann]

I really considered that and I found a bunch of used ones, but considering it is my brother-in-law's motorcycle, and they are depending on my judgement, I decided against a used one that might have the same built in problem or worse.

On the plus side ... the new ECM is mapped with all the upgrades from 2002 to present day. Not high performance upgrades but rideability performance upgrades.

No more coughing at lights, no more crazy idle patterns, no more intermittent cutting out or stalling at the end of a highway ramp.

Another thing I forgot to mention was when they were looking up the part, it superseded to the next year and then superseded to the next year and so on ... until they came up with this one number .. the ECM from HEAVEN. Every year had a different part number.

[Jack Klarich]

I really considered that and I found a bunch of used ones, but considering it is my brother-in-law's motorcycle, and they are depending on my judgement, I decided against a used one that might have the same built in problem or worse.

On the plus side ... the new ECM is mapped with all the upgrades from 2002 to present day. Not high performance upgrades but rideability performance upgrades.

No more coughing at lights, no more crazy idle patterns, no more intermittent cutting out or stalling at the end of a highway ramp.

Another thing I forgot to mention was when they were looking up the part, it superseded to the next year and then superseded to the next year and so on ... until they came up with this one number .. the ECM from HEAVEN. Every year had a different part number.

Typically with the new can bus system any update will have a letter designation starting with a - c or d depending on how many changes have been made