Bikers Workshop Series

Replacing the ECM on a GL1800.

By Steve Saunders.


Having received the Honda Service Bulletin 15 (the overheating fix) recall letter from Honda, it was determined from the VIN number of my GL1800 that only the ECM would need to be replaced. This is the minimum of warranty work that any 2003 model will need, many other Goldwings (especially 2001 & 2002 models) will also need to have the cylinder heads checked and/or replaced, and also to have a coolant gauge sub-harness inspected and/or replaced. The Honda distributor in Ireland was good enough to supply me with the new ECM so that I could fit it myself. Note that this article covers the pre-2006 model, from 2006 on the meter panel removal is different and not described here.

Click the thumbnails for a bigger image.

First task is to remove the top shelter. Full instructions (with photos) for shelter removal are given in the article on GL1800 CB Radio Fitting. You don't need to disconnect the battery before commencing this job, as the new ECM out of the packaging will not have been set up (initialized) before. More on this at the end of the page. If you leave the battery connected you won't have to reset your radio channels later on. The video tutorial in Replacing a GL1800 Air Filter covers removal of the shelter.


This is the view of the ECM with the reverse/cruise module piggybacked on top of it.

After removing the two connector blocks from the reverse/cruise module and the three from the ECM, gently pry the tabs on the mounting housing up and slide the reverse/cruise module out to the left of the Goldwing.

This is the GL1800 reverse/cruise module removed.

Now pry the single tab at the bottom middle of the housing down and slide the ECM out to the left.

The replacement ECM on the left and the old one on the right. Different part numbers and manufacturers names on the label are the only visible difference between the two units.

This is the housing with the two units removed. You can get a better view here of the tab that locks the ECM in place. Fit the new ECM and the reverse/cruise module and make sure all the connector blocks are firmly in place. Before replacing the Goldwing plastics, you will need to initialize the ECM. This is crucial to setting up the unit properly from the very start. To initialize the ECM, start the engine and allow it to warm up to it's normal operating temperature and stay running for at least 90 seconds after. If you are not sure what the normal operating temperature is, just wait until the fans come on and wait the 90 seconds after that before switching off the engine. I actually waited until the fans cut out and came on and cut out a second time before shutting off the engine, simply because I was wrestling with a cup of tea and a sandwich while this was going on. It's very important that you DO NOT operate the throttle during this time, otherwise you will need to repeat the process. A Honda mechanic informed me that failure to initialize the GL1800 ECM usually results in popping sounds, erratic idling and a higher than usual appetite for unleaded, among other things. That's it folks, new Goldwing ECM installed. Replace the plastics and saddle and away you go into the heavy city traffic, no longer fearing to trundle along in second gear at low speeds!