1993 240 Wagon
244k miles

I need help troubleshooting an SRS code.

The SRS light blinks 5 times. I've cleared it multiple times, only to have it come back on after an hour or so of driving so I think I actually have a fault that needs addressing. Code 5 seems to mean 'air bag assemble resistance too high'

I don't think it's a good idea to test the resistance of the airbag (that's a natural selection test I can pass)

While this has been happening, I had the opportunity to pull the carpets, and I checked the airbag connections running down the drive shaft tunnel and into the controller - all looked tight and clean. I have not pulled the airbag to check it.

How do I determine if the airbag is really the culprit? I don't have a spare airbag.

And the worst part is that my family is afraid to drive it now.

Thanks!

Well, I'm here almost a year later, and I've been battling the same error code from last summer: the SRS light was on, it gave the same error code (5 flashes), and I could not reset it.

To resolve the issue last summer, Dave helped me narrow things down. I cleaned up the connections with some CRC cleaner, and everything was great. And in my infinite wisdom (and perhaps stupidity), I added Bundy Penetrox to the orange connectors thinking it would prevent any further issues with connectors. Everything was great until mid-June when the light and code returned.

Here's what I did to find a cause:

- tested the resistance at all the orange connections back to the crash sensor. Greenbook says it should be 200 ohms. I was getting about 201 to 202, and I figured that was within my range of precision.

- Inserted a 2-ohm resistor in place of the airbag (there is a Volvo tool that can be found for about $40USD online but this was a cheaper option) - code would not erase.

- Unplugged the clock spring at the steering wheel, inserted a spare, and connected the airbag - code would not erase.

- Unplugged the orange connection near the transmission tunnel, inserted the spare clock spring, and connected the airbag - the SRS light reset itself! (I did not know it could do that) Now we're getting somewhere. Since I knew I had connectivity from the clock spring back to the crash sensor and reasonable resistance, maybe that Penetrox goop I used was adding just enough extra resistance to throw the testing off.

- Cleaned all the orange connections with CRC electrical connector cleaner to remove the Penetrox, and connected the airbag - the SRS light has remained off.

I'll put some miles on over the next few weeks. And I'm wondering if the Penetrox is not good for gold-plated connectors. Now that I read the bottle more closely, it says for AL/AL and AL/CU connections (aluminum and copper). Gold is not specified.

Anyway, I hope these insights add to the community of knowledge. Feel free to pile on.

Thanks.

Good to hear back that you had at least some success, although it didn't quite last one year. At least you know you're on the right track.

I wouldn't advise using a conductive paste like Penetrox in this gold-to-gold contact application. Not that it might cause a signficant problem, just it's not called for and not necessarily the most approriate for the job, so why take chances. It's not like it's got gold or silver particles in it, only zinc and copper, which can oxidize if the paste ever dries out as well as being a less than perfect layer between between the gold. For conductive pastes in an electronic application, you'd want to be careful to get just a fraction of a drop inside the female connector sleeve, like with a toothpick. Any excess could get between pins and in heat it might tend to get a bit runny.

I agree with now using a good contact cleaner to remove the paste as well as any other environmental grunge and leaving it as a gold-to-gold plated metal contact the way it was originally (that Swedish Volvo service manual I found doesn't call for anything to be used, as I recall). Rinse and repeat using a toothbrush, followed by compressed air if you've got it (spray keyboard cleaner available in dollar stores is ideal for this). I'd want to use a high quality electronics contact cleaner that is guaranteed not going to harm rubber and plastics and is residue free. Lots are advertised as safe for electrical and even electronics, but I don't trust them. I prefer to stick with plain old technical/medical grade isopropanol that's at least 99.5% pure isopropanol, which you can get at pharmacies (don't leave it open too much, it does absorb moisture). With gold-to-gold contacts on computer circuit board edge connectors, all we were ever allowed to use was a clean, white plastic pencil eraser to remove oily finger prints and canned compressed air to blow out any hairs or dust.

Now if you were starting to get Code 5 again, then if you'll recall from our discussion last year, that's indicative of too much resistance (over the specified 1.8-2.4 Ohms), not a short such as internally in the clockspring, which would give you a Code 4. As a side note, resistors have a manufacturing tolerance as well as the accuracy of your meter, so best to measure the difference between the 2 Ohm test resistor by itself and the resistor when in circuit, wanting it to stay within the +/- 0.4 Ohms spec for the wiring and connectors, or at least close to that.

If cleaning the contacts keeps you going again for another few months then you know you're on the right track and it's resistance in that circuit. If the resistance in the wiring checks out and you can reset it with the test resistor in place, you still don't know if the aging airbag gas generator is a contributing factor. NBB!!! You must not try measuring across the gas generator contacts with a meter as you risk detonation!!! Those airbags are way past their best before date, so could be getting closer to the allowable resistance limit as seen by the SRS module, and as well the SRS controller electronics are also aging. As long as the SRS light goes out, the controller is happy with the airbag, the system is enabled and it will attempt to detonate in an accident, so best to leave it as it is if you're unable to replace it.

Question, you're still using the original clockspring, right? I see in one of your later emails where you decided the replacement you got on ebay was no good (no huge surprise as it likely wasn't tested by the seller, as I had cautioned).

You also said you weren't going to play with the locking screw in yours. I believe I had previously recommended that you verify the integrity of the clockspring by checking for uniform resistance throughout its range of travel to be sure it's not got any internal problems.

I also recommended that you always reset the neutral position just to be safe. The neutral position is wound as close as you can to half-way between a relaxed spring and being almost snug (not tight, maybe tap it a bit, don't force it by hand) and installed with the steering pointed dead ahead. As long as you don't let go and have it snap back in your hands or wind it too tight, you won't hurt it any more than if you were turning the steering wheel. I wouldn't remove it just for the sake of doing it now, but do keep that in mind for the next time you've got the steering wheel off.

Note also where I had said it often takes a number of attempts to successfully reset the SRS controller (with or without touching anything else), and your 240 controller was known to be especially prone for this. If it resets on its own then great, but it's often taken me a couple of goes whenever I've had to do it.

Wishing you continued good luck now that you've got the SRS light out again.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Dave helped me systematically test and check various items found in the SRS manual he shared with me.

First we checked the contact reel (clock spring) per the instructions in the manual, and it tested just fine. We discovered a bridge clip in one of the orange connectors. We think it's to help protect the circuit. I added a picture of it to the photo stream.

Next we moved to checking all the connections from the airbag to the crash sensor. Those were pulled apart, cleaned, treated with anti-oxidation paste, and reconnected. This included all the orange connections as well as the yellow connector behind the carpet near center console. I did not detach the connector from the crash sensor. The connections all looked GREAT before the cleaning, so I was skeptical this would work.

After resetting the SRS light, the system has remained error free for over 250 miles, which is about 200 miles further than it has in the past. So I'm calling this resolved for now. There may have been something in one more more of the connectors causing more resistance than what the sensor was looking for.

Anyway, thank again to this forum and helping keep the 240 safe and running.

Onto fixing the driver's heated mirror before it gets too cold....

Jeff, excellent set of pics on the 240 airbag and connections, way better than any manual. I hope you don't mind, I'm reposting your link here as it's buried back up in a previous reply of yours.

1993 240 Airbag and SRS port pics
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

In the later RWDs, heated mirror failures are often oxidized connectors on the back side of the mirror. If you can tip the mirror far enough and get a light to see the wires then try using bent needle nose pliers to loosen (not remove), wiggle and reseat the connector. Best access is usually with the mirror pushed all the way around, the glass tipped out as far as it will go, pressing down on one of the far corners to see behind the glass with a good LED flashlight. If that fixes it then you will want to pop the mirror and properly cleanup the contacts. Mirror removal procedures vary by year and model, so look up how your particular glass is mounted in the housing and how to remove it otherwise you risk breaking something. An interim fix is to try getting some spray DeoxIT on the contacts. I think it was Randy Starkie here who got me onto that fix.

Still crossing my fingers for you on that SRS light staying out. It was a good learning exercise and I'm glad my previous experience and finding reference materials were able to help you.

The SRS light is back on after a few days.

@Dave - let me know how I can obtain the clock spring instructions you mentioned in the earlier message.

Starting today, I'll be away from the 240 for about a week, so I won't get to anything until the following week.

Thanks!

Yes, full steering travel lock-to-lock will indeed make for more movement and stress on the clockspring and earlier failure. Clocksprings often break when the steering is hard right and the spring coils are in maximum tension, such as when parallel parking. But they can break at any time if the spring has been suffering continual stress, including from age.

There's a good explanation for an intermittent problem such as yours. There are two spring coils inside the clockspring, one for each of the two wires in the airbag circuit. If one spring breaks, there can still be some continuity in the wound spring between touching metal except in certain positions, such as end of steering travel. That's why you're able to go a while after a reset. When both break, it's usually game over and no amount of resets will work. There will also be no spring resistance when the clockspring is turned by hand.

The controller needs to see a small amount of resistance in the circuit to know an air bag is present. Even with some continuity in a broken coil, the controller will get upset and raise a code 5 if the resistance isn't within the expected range. That's why the airbag gas discharge connection is recommended as the first place to check. It's the easiest place to check and any oxidation there could create such a situation.

I tried emailing my clockspring article to your user email address through the Brickboard mail system. It bounced as expected as the email system hasn't been working in recent history. Please post your email address and I'll send it directly.

I wrote the article way back in 2009 and later submitted it for the FAQ here to appear in the Descriptive file feature section, not the main sections. It covers contact reel (clockspring) testing, removal and installation. Unfortunately the article never made it into the next major revision of the FAQ as Steve Ringlee stopped maintaining it soon thereafter.

Although written for the 700/900 series, the 700 single airbag system is very similar to the later 1991-on 240s other than the contact reel the 240 steering column and steering wheel being different. You can tell the later clocksprings as they a single screw lock tab and the spiring was partly visible. The 240 orange dash wiring harness to the steering column will likely also be slightly different. I didn't check, but the control module is likely also different because components like the airbag and clockspring are different. The principles are the same.

I hope the article helps find and fix your problem. If you have questions post back and either I or someone else will try to help. I am familiar with the earlier 240s, but haven't needed to work on the 240 SRS system.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Thank you Dave. I have no intention of sharing or reposting. My email is jeffkrenek at gmail.

Now to source a clock spring (or 2!).

The only thing I had not inspected was the airbag connection in the steering wheel. (Thanks for that reminder Art!). Well that is now complete.

I did not see any corrosion or any other obvious signs that would cause the resistance to be higher than normal. I reseated the airbag connection and reset the SRS light. Let's see how long it takes to come back now.

Here are some pics I took of the disassembly today: 1993 240 Airbag and SRS port.

Thanks.

Thank you for the pointers on the connections and clock spring.

After about 100 miles, no light. So far, so good.

There are some drivers in my family that enjoy the tight turning radius of the 240, and will often do u-turns in the middle of streets, taking the steering wheel to a full stop. I assume this puts the most strain on the clock spring.

Does the turning the steering to full stops increase the wear on a clock spring? Is it possible that it only intermittanly fails near these full stops?

Thanks!

Yes, a bit of resistance in a connection can exist without naked eyeball evidence. Folks who buy DeoxIt get used to that. I was going to suggest checking for a code if you just leave the airbag out, i.e. is "high resistance" inclusive of wide open circuit? Broken clockspring? But I see you braved the removal and re-installation and the fault light hasn't set yet.

Nice pictures! Looks brand new!
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Art Benstein near Baltimore

Why don't you ever see the headline 'Psychic Wins Lottery'?

If the SRS light remains out then great. However, code 5 indicates a bad or missing ground for the driver airbag, which is referring to the entire airbag circuit. The same code is raised for a break anywhere in the wiring as well as for an open connector. Although the problem could be a weak electrical connection at the gas generator (240s are great for grounding issues), I think it's much more likely to be a broken clockspring, also known as the contact reel, a term commonly used by Volvo for 240 SRS. Normally the spring conductor completely breaks, but old ones can also have an intermittent break in the spring circuit before they finally break.

If your SRS light comes back, please reply in this thread or start a new post. I've got notes available with complete step-by-step DIY information on diagnosing a bad clockspring, removal and replacement, complete with p/ns and specifications. Do not attempt to remove the clockspring until you understand some of the subtleties, most notably locking/unlocking the clockspring and always resetting the neutral position. Videos are also available online of assorted quality to give you an idea of the project.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

The codes on my 93 240 are read from the SRS light on the cluster using the SRS test port in the center console. The OBD under the hood is not used AFAIK.

I followed these instructions.

I have no trouble reading and resetting the SRS light. I usually have to disconnect the battery for a while and read codes multiple times before it will reset.

The issue is that it comes back on after a short time with the same code - 5 blinks.

I'm searching for the best way to narrow down the cause and resolve it.

Thanks.

In those troubleshooting tips for "high resistance" it says first off to check the gas generator connector. Even though it is gold plated, I'd at least reseat it to see if that action clears the high resistance diagnostic. This is what I believe is being referred to:







I think I remember Volvo extending the life expectancy from 10 years, but I doubt very much they support it to 30. My cars are all 89 or earlier, so I seriously lack any srs experience to share.


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Art Benstein near Baltimore

A man's knowledge can never outweigh his experience.

Art, you are correct. Volvo did extend the SRS lifespan. Believe it was 15 years. Even if reseating works I wouldn’t count on the SRS system working in event of a crash. After the clockspring broke in my 90 240 I disconnected the SRS light. Wasn’t going to spend my time or a dime on fixing it and then have it not work in a crash. 240’s were very safe cars pre-airbags. Personally, I could live with that…:)
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Will I buy another Volvo??? We'll see....

I'm guessing one of the questions a DIY person would have, when working with seat belts, SRS, and ABS, even brake hydraulics, is what an insurance company lawyer could argue to save that company money in a claim. It is hard to completely put that out of your mind.
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Art Benstein near Baltimore

"The world is full of specialists that only think about one small aspect of a problem. To be a good systems engineer you have to look at the whole picture, all while keeping cost, service, and reliability in mind." - Paul Rako

Very nice 👍 - A custom made 240 airbag for pre 90 240’s….

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Will I buy another Volvo??? We'll see....

I read the instructions. I would keep trying. Consider disconnecting the battery and controller. It did say in the instructions that if it doesn't work after multiple attempts you need a new SRS sensor.
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Will I buy another Volvo??? We'll see....

Hi,

Are you talking about OBD codes?
B5 is the port for OBD DTC codes.
I don't find 1-1-1-1-1 listed in the pocket data book.

I do have the SRS wiring info from the 1993 240 manual that I can send to you.
Provide an email address.
The B5 codes report from the SRS sensor module called a "Crash Sensor"
in the 240 manual. It's under the driver's seat.

Proceed with caution when working with SRS connectors/grounds etc.
Disconnect the battery and wait ten minutes before servicing SRS grounds etc.

There's special manuals for Volvo SRS but so far I haven't seen one.

Bill

Bill,
I believe the OP is referring to the dashboard SRS light. It blinks when there is a problem that needs to be addressed ASAP. I forget if this happens on 240’s, but in newer cars the check engine light will also blink when there is an issue that needs immediate attention.

Woodshavings,
Did you clear the OBD code or disconnect the battery? Something I would try if it was my car is disconnecting the battery for at least a half hour then disconnect the controller for awhile. Then reconnect both. Don’t know if it will work but worth a shot anyway. Definitely stay away from the airbag! You don’t want it to go off (that would certainly ruin your day!) or damage the clock spring.
JW
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Will I buy another Volvo??? We'll see....

Hi Jim,

I hope your injury is healing well.

If the 1993 240 OBD setup is the same as the 1993 940
there's a series of codes for SRS at port B5.
He should start by checking codes.

Cheers, Bill

Hi Bill,

Reconstructed wrist is doing as well as it ever will. Overall, pretty happy...:) - Thanks! Moved onto other injuries. Top priority is trying not to have surgery on my other hand. How's the shoulder coming along?
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Will I buy another Volvo??? We'll see....