Got an air bag code 41. Comes on and flashes the code a number of times, then goes off for the rest of the ride. It is a 96 Arerostar, XLT, 4LV6. From what I read it is a short someplace. Where are the crash sensors and how do you check them for "shorts"? I don't understand much about the whole system.
Stavid

 

Usually that code and other airbag codes are caused by a worn out clock spring. Its not a guarantee, but its quite common for the iron to quit working and/or the cruise control won't function, which could help confirm a failed clock spring as the culprit.

 

Khan, Both the horn and cruise still work well.

 

41 Primary Crash Sensor Circuits High Resistance or Open

Air Bag System Component Location
Center air bag sensor and bracket (14B006) — center of radiator support upper bracket reinforcement

RH front air bag sensor and bracket (14B004) — cowl side panel (02038) (RH)

LH front air bag sensor and bracket (14B005) — cowl side panel (02039) (LH)

Driver side air bag module (043B13) — steering wheel (3600)

Air bag sliding contact (14A664) — behind steering wheel

Air bag diagnostic monitor (14B056) — under instrument panel (04320) left of steering column

A thermal fuse is built into the air bag diagnostic monitor. If a short to ground should occur in the air bag deployment circuit, the microcomputer in the air bag diagnostic monitor will send a signal to the fuse causing it to open. The open fuse removes all firing power (battery/backup power) from the deployment circuits. This prevents unwanted air bag deployments due to damaged vehicle wiring.
Code 51 is displayed whenever the diagnostic monitor thermal fuse is open and no other higher priority faults exist (consult Diagnostic Trouble Code Priority Table ). Code 51 is normally seen after service of a Code 13 condition.
If a Code 51 exists and a Code 13 condition has not been serviced, this means an intermittent short-to-ground exists in the air bag deployment wiring. The intermittent short-to-ground must be located and serviced before servicing the Code 51 condition.
Since the thermal fuse is built into the air bag diagnostic monitor, the monitor must be replaced to service a Code 51 condition. NEVER replace the air bag diagnostic monitor without first determining the cause for the Code 51 condition. If the short-to-ground is not properly serviced, the short may reoccur, once again destroying the thermal fuse in the air bag diagnostic monitor.

 

96 thanks for the feedback. It sounds like what I have to do is check each crash sensor for open circuit. If they are good it is likely the clockspring. I can tackle this I think. But won't feel thorough about it unless I am following a clear set of diagnostic tests. Your info looks like it comes from a service manual. Where is one available?

I have a file on the old computer named 96TRK17.iso. Many moons ago I downloaded it, can't even remember where I got it. It came as a zip. I extracted it. All good but the format seems strange and I can't open it now for some reason. Although I know I have opened it in the past.

 

that's a DVD burn image file, .iso for Ford service manual

I'll see if i can extract the air bag sensors electrical schematic from my dvd manual but it will probably be a couple days, christmas stuff going on

 

96..
Thanks, no problem with timing. I can use the guide. I tried again with "DVD image" thing. Can't get it to work. I used WINRAR to extract the iso files . When I try to install the ***** file I get the blue "FORD" screen asking where to install the files, click yes, but no files show up in the folder. I must be missing something. Or just don't have all the files needed.

I got my 98 Sentra needing a new starter and my Aero has an evap code on the cannister, I have to fix. To boot I changed the AERO thermostat a while back. I figured cooler is better, so I put in a 180F tstat. WRONG........ Car runs cool but gas mileage plain sucks. I am going to go with a 190 or 195 based on one of your previous posts. No better than 15 mpg when I used to get 17 city/23+ hiway. Then the rear wiper switch broke. Found one on ebay, only place. So I'll have things to do while waiting your info. And I do appreciate your trouble.
thanks again.

 

I pulled the air bag. Clockspring seems good. I have continuity between the terminals, and no short to ground. I also have the crash sensor unplugged from the harness (near the battery area). Question---It shows open circuit at the 2 wires to the crash sensor. Should the sensor have some/no resistance? Trying to rule the sensor good or bad. Also does the sensor have to be well grounded? It looks like over time it may have lost a good ground. About to check the thermal fuse to see if it is blown.

 

Pulled the cover on the fuse box. The fuse is dark body with a green tip. looks good, doesn't appear burnt to the eye. It is still in one whole piece. If it is burnt, will it be separated in two pieces like a normal fuse? I get continuity across the fuse, but since it is still in the circuit board, I can't trust it.

 

Some failed fuses can look continuous, so the surest way to check them is by continuity. Is it a plug-in or is it soldered in? If soldered, you need to carefully un-solder it to test it. I say this because too much solder heat can also break fuses.

 

can't find my pre 96 Aero service cd.

my 96 97 Ford Aero service DVD does no show a schematic for the air bag system, only one shown is for the Ranger which is different.

they are avail online and ebay

Chilton and Haynes manuals do not list the Aero air bag schematic.

the crash sensors are a 2 circuit system.
1 closed circuit for air bag controller testing that the sensor is still there
1 open system that closes during a crash

system requires 2 crash sensors to close in crash to set off the explosive bag.

my guess from your air bag code #41 is that one of the continuous closed test circuits is broken wire or open from poor connection.

 

The fuse is soldered into the circuit board of the SRS/airbag monitor. It is enclosed in a small plastic case. It is a thermal fuse that opens at about the 320F range, so I would expect to see heat related signs. Blackened and burnt ink on the outside of the barrel and some melting charring of the plastic case, and maybe the bright green tip would be blackened. I don't see any of that. It looks fairly good in fact at least to the eye. The crash sensor at mid radiator, has a two wire plug. One wire is shorted to ground, as is the body of the sensor. No continuity between the two wires themselves. I got a hold of a diagram on the web (supposed to be for 96 Aero/Bronco/Explorer) that shows the body of the sensor appearing to be grounded. And one of the two wires tieing into that ground at a point within the sensor itself. It is not meant to be a schematic of the sensor so there could be other components, like a resistor, in that particular wire, before it connects to the ground. I also found info that says on some sensors you are suppose to have 1000+- ohms to ground. Don't know if that applies to my sensor or not. If so, that is my problem.
I only see one primary crash sensor. I pulled the grill and the light bezels so I can peak inside the fender wells. No sensors. The safing sensor is in the monitor box I believe. One thing has me puzzled. The diagrams I have looked at --right, wrong, or in between show 3 wires from the sensor to the SRS monitor. I have only two!!!! Not good with electrical diagrams, maybe I aint seeing this right!
I am going to poke around a little more. but will likley pick up a manual on ebay. thanks

 

Code 41 update-

Finally found a writeup and diagram on the inet that seemed to match my setup. Used it to determine the following:
(air bag was pulled)
1. My sensors are good. They show 785 ohms to ground across each one measured thru the wiring harness. Book value is 785 +-10. Found the sensor at the radiator, could not find the right hand sensor, which is supposed to be around the right side kick panel. Other wiring checks OK
2. Checked the safing sensor wiring, It checks OK, no resistance to measure like the other 2. I could not find it either. Supposed to be around the left side kick panel.
3. Elec Diagram says the airbag equivalent resistance is 1 ohm. Found a few VW writeups, where folks who hate airbags pull the airbag and replace it with a resistor to keep the light/chime off. The Ford airbag simulators that can be bought new for $30-$90 are listed as being a couple of ohms. I gave it a whirl and made my own simulator from a one ohm resistor, so I could measure pin voltages at the module. Found pins same diameter as the clock spring female plug. Fit great. Cost about $3-$5 total. Parts from an industrial electronics store. Takes 10 minutes to make if you are slow. Took me 15. No soldering, I used crimped connections. Measured 1.2 ohms when finished so the connections were OK. Tie-wrapped it to the steering wheel so I could drive with it installed. Got pics and can post if there is interest.
4. With key on, measured a couple of voltage settings at the module. They matched the specs pretty close. Circuit voltage to the airbag was 2.62 vs spec of 2.55. Seems close enough. Unplugged the clockspring below the steering wheel and got a code flash, 12 I think, not sure. Plugged it back in and it stopped.
5. Cranked up and drove for 5 minutes, and then 10-15 minutes. NO AIR BAG LIGHT!!!!!!!!!!!! Turned the wheel from limit to limit more than a couple of times.
I guess I have/had a loose connection that is now tight. Maybe the airbag plug. I am going to reinstall the airbag and go with it. If I get a code it is the sir bag itself, or the plug.

I would think I can check the air bag resistance with a multimeter, and not have something weird happen. Hesitant to place an unknown voltage from the multimeter across the airbag itself. Gotta be too small to set it off. Anyone ever try?
Stavid