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Re: 98 vt srs light
Posted: Sun Apr 17, 2011 10:54 am
by vn5000
I was reading your other post the1 ,with the diag enable wire maybe the module half earths the srs light and when you connect the tech1 it fully earths this wire to enable diag.Does the srs light go brighter with the tech1 connected and communicating with srs?
Re: 98 vt srs light
Posted: Sun Apr 17, 2011 12:49 pm
by The1
hmm nar just the same as always, ive tried shorting it manually but wont light, i think the tech1 must send an enable comms command or something
Re: 98 vt srs light
Posted: Mon Apr 18, 2011 10:31 am
by charlay86
Maybe the Tech 1 provides a specific resistance on that diag enable line? might be worth trying to measure it
Re: 98 vt srs light
Posted: Mon Apr 18, 2011 11:12 am
by The1
Yeh good thought I'll go check
Re: 98 vt srs light
Posted: Mon Apr 18, 2011 12:08 pm
by The1
WIth Tech1 Connected
diag light - Srs Data pin = 66K Const
Diag light - Earth = 0
SRS Data - Earth = 6.5M normal then 1.4K on Connect/Data
WIthout Tech1 Connnected
Diag Light - Srs Data pin = 0
Diag light - Earth = 0
SRS Data - Earth = 100K
So i can see there a 66k between data and diag light pin
Ill go and make it log a code then see what it does when i clear it.
Re: 98 vt srs light
Posted: Mon Apr 18, 2011 12:32 pm
by The1
still same as above when clearing codes, so it looks like you need diag light - Srs Data pin 66k then you can start talking to it
Re: 98 vt srs light
Posted: Mon Apr 18, 2011 5:07 pm
by Doctor Bob
umm im pretty sure its a serial data signal
Re: 98 vt srs light
Posted: Mon Apr 18, 2011 6:10 pm
by The1
yeh vs would be serial data, what about VT? it's on the same bus isn't it?
Re: 98 vt srs light
Posted: Mon Apr 18, 2011 6:28 pm
by vn5000
Yeah vt srs is definitely on the same bus as pcm and bcm.
You could try getting voltages on srs light/diag enable pin with tech 1 connected and disconnected.
Re: 98 vt srs light
Posted: Mon Apr 18, 2011 8:39 pm
by jacomms
So BCM PCM SRS DASH ECC ABS all on data bus. TECH2 is needed for the SRS diag on VT. The SRS module monitors resistance and capacitance of each loop.
If you have installed a new dash cluster from say a calais you need to reprogram it to suit the SRS config too. rather than type crazy tryinh to explain I will attach the SRS extract for you. Quick note though......something as a re-soldered wire on the SRS wiring is enough to throw a code. When I was working for Holden we would have to replace harnesses rather than repair for this reason. I do have a VT Calais harness pulled apart if you would like the SRS cabling to just replace the required wires if this is the problem, just let me know from what side ....under which seat.
Hope the info helps
Justin