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DIY: 1998 Volvo V70 Clock Spring (Airbag/Horn Contact Unit)

I discovered the V70  Clock Spring was broken while changing my Ignition Tumbler and Ignition Switch.

FYI: By Federal laws, any modern cars made after 1991 or so must have Airbag in the Steering Wheel. However, with the SW turning all the time, there must be a device to maintain electrical contacts to the Airbag and Horn, regardless of SW position.

In vehicle steering systems a clock spring or clockspring is a spiral-wound special rotary electrical connector which allows a vehicle’s steering wheel to turn while still making an electrical connection between the steering wheel airbag and/or the vehicle’s horn and other devices and the vehicle’s electrical systems.

https://en.wikipedia.org/wiki/Clockspring

This is exactly what the Clock spring does, with time and mileage, the three (3) plastic legs break with the following symptoms:

  • No horn (just test your horn once a month, if no horn then likely bad Clock spring).
  • The SW Airbag will not function, but you will only find out the Airbag is not working after you were in a frontal collision!
V70 Clock Spring

GENERAL NOTES WHEN WORKING ON Volvo V70 CLOCK SPRING

  • Battery must be disconnected for this procedure! But when all done, key must be in Position II before connecting battery ground cable, this is per VADIS procedure. Doing this will avoid a dash SRS light and a trip to dealer to shut it off (Hint: mucho $ at dealer to do this for you, so heed the warning!).
  • You must read the attachment air bag restraint system.pdf by “jablackburn” in the thread below. Pay attention to section on page 16: STEERING WHEEL & CONTACT REEL: read this document a few times so you understand how the SRS system works:
    http://www.matthewsvolvosite.com/forums … =1&t=24297
  • Wear Eye Safety Goggles for your own protection.
  • I call the Clockspring as “Airbag/Horn Contact Unit”.

Clockspring Tools

  1. Long Torx Set (or Long Torx Drive)
  2. Metric Allen Key (optional)
  3. 18-mm Socket
  4. Plastic Container for tools and nuts/bolts to avoid losing them down below the seats!

Clock spring tools
Clock spring tools

Procedure

1. Set SW straight. Copy FM, AM radio channels, then D/C battery Ground Cable (10-mm wrench).

2. Remove Upper and Lower Steering Cover (See the DIY link above for detail); basically Torx #25 bolts.

3. Remove both Turn Signal and Wiper Stalks (See the DIY link above); basically Torx #25 bolts.

4. The Airbag/Horn Contact Unit is held by two (2) Torx #30 bolts. These bolts are part of the Steering Wheel and are captive (won’t fall off when Airbag/Horn Unit is removed). NOTE the mirror showing the locations of the Torx #30 bolts.
My tip: the Long Torx Key must be at least 1-1/4” deep to reach the Torx #30 bolts. Once loosened, I used the 4mm Allen key to spin it out, although this step of using Allen key is optional.

Removing steering wheel
Removing steering wheel

5. Stand outside of the car and with Airbag/Horn Contact Unit pointing away from you as shown, gently pry the connector off the back of the Unit. NOTE the wiring points downward for re-assembly.
Place the Airbag/Horn Contact Unit face up in the Rear seat away from you.

Be careful! Removal of the airbag/horn contact
Be careful! Removal of the airbag/horn contact

6. Remove the 18-mm Bolt but do not remove the SW yet!
You need to mark the SW with Sharpie for re-installation.

Almost to removal of the steering wheel
Almost to removal of the steering wheel

7. Now pull the SW and place it in the Rear Seat.

8. NOTE the Airbag/Horn Contact Unit has 3 plastic legs, which broke after 12 years/106K miles (or may be even before it, I just did not know about it!). Also note the 2 prongs that fit into the SW slots.

Airbag/Horn Contact Unit has 3 plastic legs
Airbag/Horn Contact Unit has 3 plastic legs

9. When installing new Airbag/Horn Contact Unit, note: Green and Black Connectors as shown.
The Black Tab is for cancelling Turn Signal.

Green and Black Connectors
Green and Black Connectors

10. Now install the Airbag/Horn Contact Unit, loosely tighten the Torx bolts as in the sequence 1-2-3. Then tighten #1 finger-tight, followed by #2 and #3. Doing so will prevent stress to the unit (let’s say you tighten #2 and #3 first, then when you tighten #1, you put stress in the #1 plastic tab!).

  • NOTE: behind the SW is the “Ground” Brush to maintain ground contact to the Airbag/Horn Contact Unit all the time regardless of SW position.
  • Apply small amount of grease on the metal ring of the Airbag/Horn Contact Unit.
Grease the metal ring
Grease the metal ring

11. This step is important: The Airbag/Horn Contact Unit can turn about a total of 5.5 turns (each turn = 360 degrees). So the Black tab needs to be in the middle of the 5.5 range. Spin the reel CW (Clockwise) and CCW and you will see how it works. This is how it functions when you turn the SW Right and Left.

  • Per Volvo procedure, remove the lock screw on the new Airbag/Horn Contact Unit, turn the black tab all the way CW first until it stops. See Yellow Circle.
  • Now turn the black tab CCW approx. 2.75 turns as shown (Red Circles #1-2-3), then temporarily pin it in place with the lock screw so it does not move during SW installation.
The Black tab needs to be in the middle of the rotational range
The Black tab needs to be in the middle of the rotational range

12. Now install the SW making sure it lines up with the Sharpie marks. Then finger-tight the 18-mm bolt so the SW does not slip off.

  • Note the 2 plastic prongs fit into the SW slots. These 2 prongs drive the reel of the Airbag/Horn Contact Unit .
  • Now remove the lock screw. This step is crucial, failure to do this step WILL damage the Airbag/Horn Contact Unit when you turn the SW! Place the lock screw with the yellow label as shown (this is factory position).
  • Now tighten the 18-mm Bolt. I don’t know the torque but tighten it until it stops, then give it a firm tug while using your knees to keep the SW still. The bolt has Loctite and will stay in place anyway.
Putting the steering wheel back on
Putting the steering wheel back on

13. Re-install Airbag/Horn Contact Unit, but first making sure the green connector’s wiring pointing downward as shown in Step #5 above. The green connector has 2 pins, 1 pin is for the Airbag and the other pin is for the Horn I think.
Tighten the two (2) Torx #30 bolts finger-tight.

Last Step: Don’t Mess This Up

14. Before you get too excited and connect the battery, STOP!

  • Insert the key and turn the Ignition to Position II. Don’t ask me why but Volvo says so.
    This allows the SRS system to do a self-check when the battery cable is re-connected to avoid a SRS dash light (if the SRS light is on, this means shelling out money for the Volvo dealer to reset the SRS light for you).
  • Now re-connect battery cable.
  • Start the engine and drive around the block to check.
    That is all boys and girls, not difficult if you follow the above steps religiously! Then call you mom and tell her you just did something good today, and she will say “Good Boy!”; now you can drink your favorite beers…..

asg1986 says”

“Good write up!I recently did this repair over the summer. Ever since we owned our 2000 XC the turn signal wouldn’t cancel when the wheel was turned back. This drove me crazy, and we took the car to the local Volvo mechanic who replaced the turn signal multifunction switch. This didn’t do it, so I replaced the switch again (with a used one) just to make sure. Eventually I figured it was something hidden from sight and did a little research.

 

I bought a used springclock from a ’98 S70 n/a. When I had the airbag and wheel off, and got to the springclock one of the plastic pieces was broken, allowing the assembly to move around. To my dismay the electrical connectors were different colors, and the new springclock didn’t connect with the connector. I ended up disassembling the new and old springclock, and swapping connectors (I think I had to swap the wound wiring too)… This fixed it! So nice to have canceling turn signals!”

 
 

DIY: 1998 Volvo V70 ClockSpring (Airbag/Horn Contact Unit)

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