Transistor switching and the SRS light

[Kibokojoe]

Has anyone ever investigated the use of low voltage or milli amperage to reset the A12 SRS module? Seems to me through pin 20 you should be able to transmit a current to reset the NPN transistor. Based on schematics it appears that a NPN transistor is used as a switch to control whether or not the SRS light is on or off.

[632 Regal]

I bought a 40 dollar do-dad from Shogun that resets everything, no clue about your micro voltage theories.

[whiskychaser]

Not familiar with the diagram but wont the light come on again when you remove the voltage from the transistor?

[Kibokojoe]

You would think but....there has to be a way they are resetting the switch electronically. Would be nice to have a schematic

[shogun]

not $40, $85, but it works on E34 and E32, E30, Peake does NOTwork for SRS reset on our cars, only from built year 1995, see Peake homepage.
And, they sell the SRS tool and the other tool separately.
http://www.bimmernut.com/forum/showthread.php?t=39204
Prices include shipping from Japan to Northern America, Oceania, Asia, Europe

SIR3 digital (20 pin round socket) : US $85.00
This device is for resetting BMW models built from 1987 - 2003 with a 20 pins plug interface; WITHOUT can bus. The unit resets the following functions:
Airbag / SRS Light, Service Interval, Oil Change Indication,
Works on the following models:
3-series E30, 3-series E36, 3-series E46, 5-series E34, 5-series E39,
7-series E32, 7-series E38, X5, Z3 E53, Z8,

[Ross]

If you think you have the ability to figure this out so a simple reset can be done by clowns like me who can't manage to remember when the battery needs to be disconnected I'll donate an SRS module for experimentation.

[whiskychaser]

If you think you have the ability to figure this out so a simple reset can be done by clowns like me who can't manage to remember when the battery needs to be disconnected I'll donate an SRS module for experimentation.

That sounds like the US equivalent of a N England expression: 'I'll show my arse on the town hall steps' if you can. Say hi to Arthur for me Ross

[Kibokojoe]

If they are charging $50 plus for a gizmo that resets the oil and service lights which is nothing but shorting a lead to ground for so many seconds.... how much harder will it be to figure out how to reset the SRS. I really think it is nothing more than a NPN resistor and they are resetting this resistor with millivolts on the transmission side of the #20 pin. Would be nice to have a SRS module for experimentation

[shogun]

as you want to spoil my business for the $ 85.00 reset tools
I give you some help to solve the mystery
Gale tried that in 2006 already, he got the pics etc., here the pics, but he apparently did not succeed or did not continue to work on it.
http://www.nmia.com/~dgnrg/diags1.jpg
he mentioned:
Ok. so I copied the pic of the underside of the reset tool & identifed the pin numbers they are using:

We know that the oil & service reset is done by jumping pins 7 & 19 with a wire, for 5 and 10 seconds respectively. They say in their documentation that the SRS reset is done by shorting the memory chip to clear the fault. As accurately as I can tell, the 2 additional pins they have in their reset tool are pins 12 & 16. I checked the schematic & neither 12 nor 16 go to the SRS module. Anyone have a parts car that will power up to practice on? I don't want to risk messing mine up by experimenting with it while it's functioning properly.

[Kibokojoe]

Isn't 7 the ground?

Are you looking at the same Electrical troubleshooting manual?