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 get zero resistance on the yellow air bag connector on the steering column leading to the clock spring.

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.

 

The schematic I am looking at for a 95 Aerostar Air Bag Diagnostic Monitor doesn't show terminal 14 for some reason. It shows terminal 13 as battery power, and it shows 18 as a wire coming from the front radiator crash sensor. It shows terminals 2,3,5,7 all being ground. What do you get between 13 and terminals 2,3,5,7?

 

Thanks for asking. The yellow at 13 is hot at 12.7 volts in relation to all of them on the connector with computer unplugged and also with computer plugged in with key off.

With key on, all are hot at 12 volts plus except the black with yellow strip which is 4 and that is very low volts at 0.3 volts.

Any ideas? Do you have access the debugging logic and the two schematics which I linked to below for the mustang, but for the Aerostar?

 

This is all I have.

 

Thank you for the diagram. You are kind to post it.

The debugging sequence would be helpful, but at this point I guess I will assume that the air bag diagnostic monitor is broken, since the battery voltage is not low anywhere I know to measure it.