Air Bag Project

by Scott Fabre

 

Last Update: 08/03/2005

 

 

The symptom was a "INFL REST" indicator light on the DIC. The code I read out was 16 indicating LH sensor fault.

 

I fixed the Drivers side Air Bag sensor (SIR) to ground problem by removing this sensor, cleaning the ground surfaces and applying dielectric grease.

The following pictures tell the story of how I did this.

 

Also included are several problems encountered and resolved.

 

1. Bad battery connectors. (replaced)

2. Bad grounds on accessory lead coming from battery and ground strap coming from the LT5.

3. Made a workaround to the difficulty of removing the panel with the gill slits such that next time it will be easy to remove.

4. Added theft protection plate between the gill slits and the battery.

 

This is just the "before" picture.

 

And here we have the tire removed.

Are you getting the impression I left

out no details :)

 

Using a 10mm for the initial

fasteners (upper left) and then

a T-30 for the three screws

and a T-15 for the small two

screws.

 

With all fasteners removed the

wheel well rear component can

be removed.

 

Notice, now the rear wheel well

part is out, the battery hold down

bolt and battery have been removed

and the lower side cover has been

lowered. The lower side cover was held in with half dozen small bolts (8mm head) on the under side and then several T-15 screws on the side. (accessible by opening the door).

 

This is the last bolt holding the

battery tray. It was a mutha

(technical term for difficult). I

thought it was going to break.

It is easy to see why we have

problems with the sensor and

ground integrity on the side of

the battery. The sulfuric vapors

and overflow goes into this area.

Lots of signs of corrosion

everywhere in this area. Needles

to say I used some anti-seize

compound on this bolt putting it

back in.

 

Now removing Mr. Sensor.

The rear bolt is 10mm and

the front is 13mm. This I

surmise is not an accident.

The wholes on the tabs (below

pictures) are also of different

sizes in order to aid in keeping the

sensor facing the right direction.

Otherwise the air bag would only

deploy when you are it from the rear.

 Kind of defeats the purpose.

 

Signs of corrosion on the flange

along with hardened dielectric

grease. (I think)

Overexposed picture but you can

see the corrosion and hardened

grease on the right flange.

Other grounds (battery ground left

and LT5 ground right) were also in

need of maintenance. These were

removed, cleaned, greased and reinstalled.

 

Another look at the corrosion.

Notice, not only is there paint under

these two ground points (battery

and LT5 grounds) but look how

thin the metal is that the screws

go into.

 

The threads on these screws are WAY TOO COARSE to be used in such thin metal. I changed these on final assembly (later) to a fine threaded bolt. The left one has been cleaned. The right one has not been.

 

I used a very fine grit wheel to

remove the rust and paint from

all the contact areas. Seemed

like the right thing to do.

Seems to me an oversight by

the general to have paint under

these contact areas.

 

See how shinny? I resurfaced

each on the tabs I found including

ALL of the tabs on the accessory

junction between the battery and

the fire wall.

 

Paint and corrosion removed.

Ready for grease.

Better view of all four. Notice

how the sensor mounts have

a captive nut attached to the

inside of the beam.

Shinny, so shinny. All ready to go

back in.

 

Now all greased up.

 

All back in now ready to button

it up.

 

I got side tracked a bit. The battery

lugs needed to be replaced.

I happen to have some laying around. Cost me 55 cents in 1984.

 

I cleaned and applied dielectric

grease to all the tabs on the

accessory lug (shown behind).

 

Accessory lug shown with tabs

removed.

 

Another side track. I placed a protective plate on the inside against the gill slits to protect the battery from being pierced. This used to be a way of defeating the alarm by the bad guys as most of you will remember.

 

Notice the reworked slot on

the inside of the panel. I added

this lug assembly so that I would

no longer have to use the bolt that

fastened from below. The problem

with fastening from below is that

you have to remove the lower

side piece to get at the bolt.

With this arrangement all I have

to do is remove all other fasteners

the push down and pull out on the

panel to remove it.

 

An even closer look ant eh modification. The protruding part

of the bolt fits through the whole in the mounting flange. (not shown)

 

I also added this rubber tube to the vent

at the top of the battery. The idea is to

vent the vapor away from the car's

electronics.

 

 

 

So that's it. The SIR sensor grounding problem is now gone. I reset the codes and test drove it and all is well.

A side benefit of the work with the tabs seems to have been more stable dash lights at idle when at a stop sign.

The dash lights used to change intensity as the alternator kicked in and out. Not no more!!! :) cool.

 

 

  Disclaimer:  Repairs and techniques are reported here by amateurs and professionals as an informational opinion service only and should not be attempted by other than factory trained and certified technicians. The ZR1 Net does not recommend anyone doing these procedures and is not responsible for any adverse outcome. Factory repair manuals should always be used and followed to the letter in conjunction with any repair or maintenance performed. All cautions and warnings that appear in the factory manuals apply here as well. As recommended in all service manuals, proper eye and body protection as well as proper tools must be used for any maintenance performed by individuals. Working on automobiles is dangerous and could result in personal and/or property injury. If you do not have the proper tools or know-how, you should not do any of these procedures, but have a qualified technician perform the work.  
   

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