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1996 850R Receiver and/or Fob remote locking

Help, Advice and DIY Tutorials on Volvo's P80 platform cars -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, including 850 R, 850 T-5R, 850 T-5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

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nickm
Posts: 18
Joined: 2 March 2013
Year and Model: 1996 850R
Location: Sydney Australia

1996 850R Receiver and/or Fob remote locking

Post by nickm »

I have non functioning remote locking.
I have just replaced the alarm relay and the immobiliser is now operating. Everything works fine with a key but I can't tell if the fob or the receiver unit is at fault for the remote.
So I just bought this
http://www.jaycar.com.au/productView...UBCATID=1041#5

2 questions
What does the locking circuit need to see to work, momentary or latching signal?
what frequency does the original fob work on? i would like to program the new receiver to the original fob (if it works)

thanks

nickm
Posts: 18
Joined: 2 March 2013
Year and Model: 1996 850R
Location: Sydney Australia

Post by nickm »

The aftermarket unit does not alter it's pulse length. It was not expensive.

So i will get another receiver unit and fob so even if the current fob works I will have 2.

If I bridge pin 5 to pin 3 quickly it will lock and a bit longer it will unlock......

Here is what I found for future reference.

"The connector for the receiver, behind the glove box is designated 4/19 and
has 5 pins:
pin 1 - wire black (ground)
pin 2 - not used
pin 3 - wire yellow/green (receiver output)
pin 4 - wire yellow/violet (+12V accessory)
pin 5 - wire red (permanent +12V)

The receiver puts out a 100ms (milli-second) positive going pulse on pin 3
to lock the doors and a 200ms pulse to unlock. There was a tolerance of
something like +/- 50ms - I forget the exact figure and it is probably
different for lock and unlock.

You stated that when the failure began the doors would lock (short pulse)
but not unlock (long pulse) - you seem to have made a mistake in your typing
and that's how I interpreted what you wrote. But it doesn't matter anyway.
It looks like either 1) the pulse former in your receiver is "out of spec"
and no longer sending the correct length pulse to the car's central locking
system or 2) the car's central locking system is no longer accepting the
"standard" pulse lengths for lock/unlock. "

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