Interesting Occurrence

[Glacier991]

Those of you who know me know I have my Explorer, and also a couple other vehicles, one a 1993 3.0 SFI Mercury Sable. Recently I had fuel pump issues, which it turned out were related to a bad "Control Module". This pricey little "module" was for some reason a FORD idea to lump all the relays (fuel pump, cooling fan, EEC and probably a few more as yet unknown) into one package. If a relay went bad (like my fuel pump relay in it did) you replace the whole ****aree for about $150. (Not $15 for just a FP relay like in my 1992 Explorer)

I digress. About a month after fixing this problem....during which time the car has been operating flawlessly, with about 120K on the clock I should add... my daughter is driving the car home one night and says out of nowhere the battery light came on, and the airbag light came on. The battery light apparently went off pretty quickly but the airbag light took a few seconds. NO driveability issues.

I pulled codes today. Zip. All pass.

I'm thinking some power related glitch caused the car to act as if the power had been turned off and then back on... the battery light and airbag sequence certainly fit that picture... like at startup.

Assuming I am right, what might cause that? Could my new controller be causing me a problem? Or is there something I am not considering? Be curious to know what you electrical gurus think.

(I am half wondering if there was some issue in the EEC relay in the controller box too brief to cause a driveability issue.)

 

[Pdwight]

Just thinking out loud here

But if the relays are all traditional mechanical coil and contact relays, probbly not that. but if the relays are solid state or SSR that use Triacs or Diacs to handle the switching they could be flaky and turning on and off when they shoudl not....I find SSRs to be great due to size and no moving parts...but far more sensitive to EMF and static.

Dwight P

 

[MONMIX]

insufficent battery power will trigger an air bag light on some vehicles.

 

[Runnin'OnEmpty]

Yep Glacier, I too am thinking battery voltage spike. If there's a cell shorting out, that might drop the voltage enough to illuminate the trouble lights. If so, you'll know it soon enough when the battery finally dies.

The only other thing that comes to mind is a wet air-bag trigger sensor, maybe from driving in rain.....? However that wouldn't explain the battery light......

ROE

 

[Glacier991]

The battery was what I was leaning towards. For now I just swapped cars with my daughter and am awaiting a repeat. Probably kinda stupid for if it occurs exactly as she described, I am not sure I would be any smarter.

PDwight I inisially assumed the module would in fact be as you described, a PC board with electronic relays. However the box that houses it is about 4x6 and maybe 2-1/2 inches high, for all the worls looking like a housing for traditional relays. It is seam folded and riveted, so it was not emant to come apart. I should have cut it open - in fact if it is around still maybe I will... and just do a little piece on relays.

 

[BrooklynBay]

This module isn't a new concept from Ford. I used to own an 89 Mercury Sable, and had a front end collision. That module got crushed, and shut the car off instantly. I wasn't able to drive as a result of those relays getting damaged. The first step Ford took at shuttting down a car in a crash was the inertia switch. The second was this integrated moule. All relays inside of it are mechanical. It would be an interesting project if anybody wanted to make an aftermarket replacement of one of these with standard plug in relays. If one of them went bad, you could replace an individual one instead of making the dealership's parts department richer everytime a relay goes bad. When I bought one of these modules in 91, it was $137. The junk yards have tons of them, but you would have to match the correct #s to get the same one. They vary depending upon the engine, options (A/C, or no A/C), etc.

 

[410Fortune]

an interesting project if anybody wanted to make an aftermarket replacement of one of these with standard plug in relays. If one of them went bad, you could replace an individual one instead of making the dealership's parts department richer everytime a relay goes bad.

Hmm...

How about use an Explorer relay box and cut all the wires, re-route them into the box.
BAM, seperate plug in relays.

Just need the wiring schematics for the module and their functions.
How many functions are we talking on this Sable? How many wires?

 

[gijoecam]

If it's a one-time occurrence, I wouldn't worry about it. If it starts happening again, then I'd start searching.

My guess would be a puddle splashed water onto the alternator, causing the belt to slip a bit and the light to come on. The system may have thought the battery voltage was low and decided that deactivation of the SRS was in-order. Once the electrical problem rectified itself, the SRS OK'd the system and it came back online.

With the lights out, I wouldn't worry. Even if the alternator's goose was cooked, you'd still have the reserve capacity of the battery to limp along on.

-Joe

 

[410Fortune]

a 93 is getting up there in age, you can expect all sorts of "quirks" from the factory wiring as the miles and age increase.
I have rebuilt my alternator harness in my BII about 4 times now, recently I completely re-routed and rebuilt the whole thing.
I noticed over the years in my quest for junk yard connectors that Ford increased the wire size twice in the later model BII's and Rangers, so apparently they also knew there was a problem....

 

[BrooklynBay]

Here is a link to an article with internal pictures, and a schematic diagram of the inner working of that module. It has Bosch relays in the pictures. I was surprised. http://www.turbotbird.com/techinfo/New_IRCM/IRCM.html