I went out again today to investigate my Explorers Airbag wiring and to do some continuity tests of the wiring harness - the wire harness portion between the Airbag Computer (Restraint Control Module (RCM)), located behind the kick panel of the front passenger seat, and the yellow dummy resister plugs located under the driver and passenger seats. First, of course, I disconnected both battery cables and waited a few minutes so that the backup power-supply in the RCM could safely discharge and render the airbags inoperable...just to make sure I wasn't going to somehow set off any airbags with testing probes from my multi meter.
As a reminder, I was getting an Airbag light code of 36 - which usually indicates a problem with the
drivers side wiring/yellow dummy resistor plug.
But at the same time, I knew that I actually had a broken wire on the
passengers side airbag wiring, right as the wire goes into the dummy yellow resistor plug...but I was
not getting a code 37 (passenger side airbag light code)????
For my 99 Explorer, I had the following wire colors going to the dummy yellow resistor plugs:
Drivers Side - Brown / Blue & White / Blue
Passenger Side - White / Yellow & Brown / Yellow
On the RCM, the wiring went into a connector:
I had previously made a simple repair of the
passenger side dummy plug broken wire (Brown / Yellow) by wrapping it and taping it with electric tape (not an ideal repair) and began testing continuity between the gold pins of the
passenger side back to the corresponding hole on the RCM connector (Brown / Yellow) (Note: my probe points were too thick to get into the small holes of the RCM connector and I couldn't find any paperclips - so I used bread loaf wire ties (pulling the plastic off the ends) as a simple conductor that would fit into the small holes of the connector). I then started continuity tests of the Brown / Yellow wire and I was getting positive continuity tones on my multi meter when touching the gold dummy plug pin of the Brown / Yellow wire and the corresponding other side at the connector...
but I was also getting positive continuity tones for the White / Yellow wire gold connector as well?? I reversed the bread loaf wire to the White / Yellow wire and the same thing happened at the gold contacts....no matter what side I was probing, I was getting continuity positive tones on both gold connectors???
I thought I might have a problem at that point but could not figure why this was??
I then switched over to the drivers side and tested the Brown / Blue & White / Blue wire pairs. I only got positive continuity tones on the white / blue pair of wires. I was getting absolutely nothing on the Brown / Blue pair. While holding the dummy connector and trying to probe the gold connector on the Brown / Blue wire, I would occasionally hear a positive continuity tone but thought my probe had just touched the other gold connector...but then realized it only occurred when I was moving the wire around. After a little deeper inspecting, I noticed a small crease, that you can barely see in the above picture, just before the Brown / Blue wire goes into the back of the yellow connector. As I bent it more, I could see copper inside. Ah Ha!
A clue!
I stuck my probe in there and started getting positive continuity tones back to the RCM connector on both the Brown / Blue side
AND the White / Blue side
I then took apart the connector (BTW, the red insert, just pulls right out with a good tug from needle nose pliers - you then have to stick a small probe into the front of the yellow connector to lift a tab, that lets you pull the wire out the back - see previous pic in an earlier post above).
See that small break in the Brown / Blue wire below...that's where my 37 code was coming from!
I then proceeded to take apart the wire from the gold pin and make another jury rigged repair of twisting bare wire from both sides and using tape to finalize the
temporary repair. All continuity tests worked perfect. Now, why a positive continuity test from the gold connector of the Brown / Blue wire goes back to the RCM connector and tests positive for continuity at both the Brown / Blue side
AND the White / Blue side of the RCM connector is beyond my understanding as to
why...
I then connected the RCM connector back to the RCM and then plugged in both resistors to their respective dummy plugs (Oh, both resistors read 6.9 - 7.0 Ohms when I probed them - I believe that is within specs for the resistor connector on the dummy plug). I then connected the battery terminals and reached in to start the car (keeping my head and body away from the front of the airbag!
).
Wouldn't ya know it!... The Airbag light came on during startup and lit up for a few seconds and then it went out. I sat there waiting for the next few micro-seconds for the typical
blinking airbag light...and there was
NONE!!
Yes!!
For now, I just wrapped up both wires and shoved them back in the holes of the carpet from where they came...I hope to never see them again but as we know, these things keep occurring. I think I'm just going to one day, cut them about 10 inches from the RCM connector and correctly solder the cut ends with the resistor dummy plugs and leave em' right there next to the RCM just like the replacement harness does from the 2003 TSB.
