SRS light on

The contacts where the clip is mounted, this is the connector for your yellow wire. I suspect this clip shorts out the airbag detonator circuitry. If the connectors were “floating” it is possible for static to trigger the bag. When the connector is inserted that link is broken & the remaining circuit takes its place.
I’m not implying that your problem revolves around this, just it is an avenue to explore.
M

That metal spring which is folded over has 2 functions:
- to firmly hold block connector in order to have good contacts on pins, since small resistance on pins will produce error
- second it makes short connection on airbsg wires when connector is disconnected in order to remove any residual electricity from 2 wires for airbag circuit not to be able to triger the airbag when connected back

EDIT: I just saw that we have reply before mine.

While I was writing above reply, it hit me that I forgot important thing:

When you disconnect block connector from DCU it is designed to do the same thing: it puts metal cross-connection over all terminals within the block connector in order to remove any residual electricity from any wire and prevent accidental detonation of airbag/s. That is the reason why you have connection you described on any terminal you try to measure. 

Point is you cannot measure wires in this way, since you will have connection from all wires. You would need to have male connector connected to block connector in order to prevent metal cross-connection to come in effect and them measure on male connector backside exposed terminals.

It was some time I was doing inspection in situ regarding SRS and this slipped my mind. I butchered one old DCU and removed male connector from it to use it as test rig.

I am sorry for this.

.

What bothers me is that when you made testing on the rotary coupler with block connector disconnected from DCU side, that means you had no resistance from first wire coming back as no resistance on second wire. That would mean you do not have unnecessary resistance on the wires. However you said that with original airbag and with 2nd hand airbag you still have same result and same error of high resistance on drivers airbag circuit. I do not have answer for this - it is strange.
At this point I would be tempted to take DCU from working car and test in this and see if I would see the same error.

Hi Roverlike and Airportable

Thanks for those replies, even i,ve had a light bulb moment.
In an ideal world it would be great to try a known dcu but that won't happen.
I'm thinking of buying a secondhand dcu and if it doesn't cure the fault i could butcher it and use the pins to carry on testing.
Also would i need the harness connector into the rotary coupler to do a proper coupler test.
I suppose if i've got the male pins into the dcu i can test straight through to the airbag connector.
If i don't the above i was wondering if i could do a needle test on the harness to do these tests, but it may be difficult on the dcu block harness.
Regards
Pete.

You may already be aware of this as it has been touched upon. If you borrow another unit & there are lots about, these will, in all probability be single airbags. This doesn’t creat s problem, unless your main problem is in the “passenger” circuit, simply leave that out of your test routine.
Where abouts are you? I have parts you can borrow (some you can have!) if you wish.
M

Sorry Roverlike, I didn’t wish to steal your thunder, I should demure to your greater knowledge but sometimes there’s an itch which one has to scratch.
That was one irritating itch.
M

Hi Airportable

To borrow or buy good known parts would be a great help, of course i would pay for postage. My thoughts have always been towards the dcu or the coupler.
I live in St Leonards Dorset a few miles from Ringwood. 
The car has only done 50000 miles so in the case of a coupler i could be buying something that has done a lot more work.

Regards
Peter.

What a lovely part of the country, It's a while since I was down there, which generally indicates a return visit.
I have spares tucked in corners around workshops & garage, the boxes containing these are in the deepest darkest corner. The only problem is I need to get the car out & its not ready to come out quite yet. I'll shimmy round to see how accessible they are & report back.
M

A positive result so far, but we need the input from Roverlike.
Apparently there are order numbers for spare & there are part numbers, these are similar & I can only assume that one number acts as a “check sum” for the other.
So, two devices located up to now & both were bought as “working & tested” dual.
They are both PR3 RC5 YWC001600.
Neither has been in my car, bought as spares, my car is dual equipped & I want to maintain its equilibrium & so these live in hope, to be fitted in case of trouble. I’ve no inclination to create trouble, hence I haven’t taken the car to bits to test.
The singles will turn up in due course but they are considerably more difficult to locate.
A bit positive; a curates egg.
M

YWC001600 is dual airbag DCU.

Doing well so far.
M