Searched other threads and internet, but no details on how to trace a low voltage causing an air bag diagnostic error code of 12 1-2. Any help appreciated!

My aerostar 1995 has low voltage on both pins 13 and 14 at only 2.8 volts. Voltage at pin 18 in 12.8 volts.

Pin 13 and 14 are only hot when key is in run position.

Pin 18 is hot all the time.

Pin 13 and 14 have no voltage at all if the airbag is disconnected using the bright yellow connector that runs up to the steering wheel column. This is true even if the key is in the run position.

I have reset all the connectors I can see. Fuses 5 and 10 are good.

I did find a interesting air bag code 12 schematic here but it is for a 95 mustang.
http://www.veryuseful.com/mustang/te...ode12Schem.jpg

More here:
Mustang 1995 Air Bag Diagnostic Codes

I also found this which mentions 2 different levels of low voltage on those pins for a Crown Victoria 1995, but it does not describe wiring enough to debug the aerostar wiring and uses different fuse numbers and amperage.
http://www.justanswer.com/ford/5xygw...bag-light.html

This would be the step I need for the Aerostar:
Check 10A battery fuse feeding air bag diagnostic monitor harness connector Pins 14 and 13.

Check power distribution fuse feeding the 10A fuse.

Is either fuse blown?

No
LOCATE and SERVICE open Circuit 38 (BK/O) or 937 (R/W) between positive (+) terminal of battery and Pin 14 of the air bag diagnostic monitor harness connector. Check in-line connectors, crimps, etc. CONNECT air bag diagnostic monitor. CYCLE ignition switch . PROCEED to the description, schematic, and pinpoint tests of the diagnostic trouble code that is flashing.

I guess what I need is other points to check voltage to see what is pulling 13 and 14 down to 2.8. I guess it could be the electronic module, but I would like to know how to test it for sure on an Aerostar.

 

Possible you have a clockspring problem, i.e. the moveable contacts within the steering wheel housing. Clockspring contacts wear, get bent or lose tension over time. Would give low voltage readings. Here is a link on how to test.

 

Thanks for the suggestion. I checked the resistance and it was correct in that the clockspring has no resistance.

Do you have access to the Ford manuals to diagnose a 12 error?

 

My manuals are 1991, pre airbag models and do not cover these diagnostic codes. Perhaps someone else here can help out.

 

OK, thank you. I hope someone has access to the computer manuals.