98 vt srs light

[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?

[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

[charlay86]

Maybe the Tech 1 provides a specific resistance on that diag enable line? might be worth trying to measure it

[The1]

Yeh good thought I'll go check

[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.

[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

[Doctor Bob]

umm im pretty sure its a serial data signal

[The1]

yeh vs would be serial data, what about VT? it's on the same bus isn't it?

[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.

[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