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

[cn90]

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

1998 Volvo V70 PN is 9157268.

First, thank you to all those who gave me the tips/tricks before doing this job.

This topic of Replacing Clock Spring for Airbag and Horn has been covered in different forums but not in great detail. So I will write it up in detail.
I discovered the Clockspring 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. This is exactly what the Clockspring 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 Clockspring).
- The SW Airbag will not function, but you will only find out the Airbag is not working after you were in a frontal collision!


OTHER USEFUL READINGS:

DIY: 1998 Volvo V70 Ignition Switch & Cylinder Lock Replacement:
https://www.matthewsvolvosite.com/forums ... =1&t=34472

DIY for 1999-2000 S70, S80 models:
https://www.matthewsvolvosite.com/forums ... hp?t=13514

http://volvospeed.com/Repair/ignition_S80.html

GENERAL NOTES:

- 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:
https://www.matthewsvolvosite.com/forums ... =1&t=24297

- Wear Eyes Safety Goggles for your own protection.

- I call the Clockspring as “Airbag/Horn Contact Unit”.

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

98-Volvo-Clockspring-01.JPG (80.6 KiB) Viewed 16393 times

PROCEDURES:

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.

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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.

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

98-Volvo-Clockspring-04.JPG (120.69 KiB) Viewed 16390 times

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.

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

98-Volvo-Clockspring-06.JPG (71.86 KiB) Viewed 16393 times

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.

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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.

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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.

98-Volvo-Clockspring-09.JPG (127.67 KiB) Viewed 16393 times

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.

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…..

[cn90]

Autopsy of the Airbag/Horn Unit:

1. Note the "Ground Tab", which maintains Ground connection regardless of SW position.

2. The Reel has 2 wires in it, so it is clear that 1 wire is for Airbag, and the other wire is for Horn.
Interesting that the Larger Green connector (rectangular) can only be connected one way, but the Smaller Green connector that goes to SW (with 2 pins) seems to be reversible and can be connected wrong if one is not careful about it!

Considering that this device performs 2 important jobs:
- Horn (this could be life-and-death) and...
- Airbag
I'd not consider fixing this at all. It is a crucial device that you only find out whether it works or not until it is too late!
So if your horn does not work, investigate further!

98VolvoClockspring10.jpg (125.73 KiB) Viewed 16375 times

[jblackburn]

Alright, we should just let you be in charge of the repair database. We'll give you a car that's entirely broken and just let you fix everything on it and do a write-up. You're procedures are way too organized; they make mine look like I'm a slob with my tools spread everywhere

[asg1986]

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!

[cn90]

I forgot to mention that antoher source for the long Torx#30 (to remove the Airbag Unit) is Irwin 3523331C Torx#30.
You can find it at Menards Hardware store (not at Home Depot or Lowes), or online for $2-3.
It fits perfectly in there.

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[cn90]

Some correction about the circuitry, glad "gdog" replied on the other Volvo forum:
http://volvoforums.com/forum/showthread.php?t=48052

----------

by "gdog"...while your post here has lots of good detail on how to replace the SRS clock spring, there's some serious mis-info there too.

The clock spring has two conductors; both are for the airbag; pwr and return. Neither is for the horn!! The horn connection is made through slip ring that you said is for the ground connection.

Also how was your clockspring broken? If either of the conductors were broken, you should have seen a SRS fault lite on your instr cluster!! The SRS system does a POST (pwr on self test) upon every key-on. And again the horn circuit is completely separate and unrelated to the SRS circuitry!!
greg

Thanks for the info! I learned something new!

The clockspring was broken at the 3 plastic mounting prongs. So the ground contact was lost ---> NO horn, however according to your note, then the airbag circuit was still OK even with lost ground circuit on the clockspring.

Thanks again for the info!

[JeffersV70]

Just replaced the clockspring on my '98 V70 and wanted to thank you for this write up. It's spot on, and it give me the confidence to tackle this myself. No SRS light after reconnecting the battery in position II, saving me an expensive trip to the dealership.

[djc126]

Hi cn90.
Nice writeup.

Does someone already have their steering wheel off and could take a more detailed closeup pic of the "ground brush"?
Or maybe you've tried taking apart the a steering wheel assembly before. Tried finding more info online but there doesn't seem to be anything.

I replaced the clockspring on my 98 S70 (SRS light on due to bad squib DTCs - clockspring was hanging on steering wheel spindle and all three tabs were broken) and found that the steering wheel ground brush is not complete on mine.

All I found was a small spring and rounded brass/copper button (see cn90's pic above). Inside the back of the steering wheel hole is a plastic post attached to a wire that continues to the front recess (it's attached to the lower right area) where airbag goes. I greased up the spring with vaseline and stuck it in for now.

But what connects the parts together?
I cleaned up the car but couldn't find any more pieces.

Trying to avoid buying a replacement steering wheel as it's not easy getting used parts in my area.

The SRS light I still had to reset (I did put key in Pos II before connecting BATT neg but it didn't work, got DTC SRS-212) and light didn't come back on during a test drive. However, the horn would suddenly come on by itself like before when turning.

The horn does work fine by itself.

FYI, although it's a good idea to mark the position of the steering wheel before removal, the clockspring already gives you the position to put it back on. This is the due to the black tabs for the notches and you can only mount the clockspring on one way. It also confirms that you've wound the clockspring correctly.

I bought this car used and it's basically sat in the parking spot while I try to fix a few minor issues on it.
Thanks.

[cn90]

djc126,

I took this picture from an existing ebay listing (SW from a 1994-97 850, so it is NOT from my car), anyway, this pic shows you the ground brush.
If yours is worn out, then I guess you can make one ground brush yourself using some hardware store stuff.

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