I have some questions about the operation of the restraints control module, (RCM).

First, a disclaimer. Restraints are a safety critical system. I fully understand this and I expect everyone else will also respect this. I will take any and all info at my own risk and I do not offer any liability to anyone else. By extension, any info posted here by others does not extend liability to them. Use this at your own risk. We are all on our own here. If you post a reply, please refrain from mysticism, fear mongering, and advice to just go to the dealer. I am hoping for a technical discussion.

It would be a good idea to start by reading this;

Airbag Control Module Download

With that out of the way, I have been investigating the function of the restraint control module during the repair of a 1998 Ford Ranger. Truck had a light front collision that set off the airbags. Different years and models of Ford trucks may have differing systems, but as far as I have been able to determine, 1998 thru 2003 are quite similar.

I have diagnostic software that can access the RCM and reset trouble codes. Focom software and I highly recommend it. Reading my 1998 Ranger RCM initially produced a DTC 1231. Focom tags this as crash detected.

Other reading suggests DTC 1231 indicates a full memory, presumably crash data and this cannot be erased. This perhaps is in keeping with legal requirements. My reading also suggests that if you can reset DTC 1231, you may erase all recorded data. Focom software can do this, but no concrete answers have surfaced.

The retention of data is of concern in that the RCM reportedly must be replaced after airbag deployment. Other sources indicate a reflash is all that is required. I suspect that clearing a DTC 1231 is as close to a reflash as you will be able to get with an RCM. There also are suggestions that the RCM contains VIN info. I have not been able to read any VIN info from several different RCM's. I have tried an RCM from a 2000 Ranger in the 1998 Ranger in question, it functions perfectly and reads no DTC's. If previous crash data is retained, I do not think that it is of any consequence and will be rewritten in the event of a new crash.

Part numbers seem to differ from one vehicle to another. The 1998 Ranger carried part # F59F-2C018-AA S. The 2000 Ranger carried part # F87F-2C018-BA S. Both were not identified by Focom software, update info has been sent to Focom. I had previously updated their data base with my 2003 Ranger Edge and I was able to identify and read the RCM. It identifies the part # as 1L5A-???-AD. This all would suggest that there are some differences between the years in the RCM, but as of now, the 1998 Ranger is carrying the 2000 RCM and all checks out. Does anyone have any info on correct replacement part #? I think the first 4 characters speak strictly to the year and the second number identifies the actual function of the part with the suffix indicating revisions. Other than the number, parts were physical identical in all respects.

Right now, the Ranger has been repaired and appears fully functional. I have confidence in this, but there is plenty of commentary out there that this must be left in the hands of the dealer, or specifically trained persons. With respect to that, I need some convincing evidence that there is a reason to put my finances at risk here. I have the capabilities to delve deep into the data, even without so called training and I have not found any evidence of this yet, so I'm putting the question out there. School me!