ABS Light & ABS Troubleshooting
 

I have a 1992 Volvo 240 wagon, and just recently the ABS light started coming on. Although it's not a steady light at times, and will go off or sometimes it blinks, but usually it's on solid. I did a little research on the matter, and there could be sensors that need cleaned, but I'm not sure how to find those sensors or how to go about cleaning them. Another possible cause is a fuse to the ABS module its self that's located somewhere under the front passenger seat, but if it's a fuse, I would think the light wouldn't blink.
So, what do you all think? Sensor or a fuse? And if it is a sensor, how would you go about cleaning it?
Any advice would be greatly appreciated,
Evan Piveral

If you take your wheel/tire off and look around the hub you'll find the hydraulic brake line and the wire going to the sensor. That's it! Follow it to the sensor and if it's a porcupine with metal shards, clean those shards off. Sensor is a strong magnet. Naturally you'll want to inspect the wiring for damage as well: I had an oldsmobile once where the wire snagged on the ball joint threads of all things.

Thank you for the response! I very much assumed it must be one of the sensors, because the light varies. Hope my wiring isn't caught in anything... sounds like that'd be a pain. I'll post back after checking sensors and let ya know if that fixed the issue or not.

Also, check your voltage. An overcharging alternator may make the ABS and SRS lights flicker.

I cleaned the two front sensors, but couldn't clean the rear because the Bentley Manual mentions something about lead seals needing replaced if you remove the sensors, or, you can clean the sensor by removing the caliper. Not sure where to get a lead seal, and a caliper would be a pain to remove, so I can't clean the rear sensors. I still assume it's a sensor, because when it rains, the ABS light will flash. I believe this is probably due to water getting in with debris interfering with a sensor. I was wondering what someone would recommend I do about the rear sensors?

under your hood, near the front side of the front suspension tower, is the diagnostic block. normally, this is used for ECU (fuel injection) on pin 6 and ICU (ignition) on pin 2diagnostics, but there's also ABS diag codes on pin 3

see Brakes: ABS

basically, key off, jumper in pin 3, key on but don't start car, press button on diag box for 2 seconds, release, and it should (slowly) blink out a code, consisting of 3 groups of blinks. 1-1-1 means no code. after reading a code, press the button for another 2 seconds and get the next code, if it repeats the first code, you've read them all.

then press the button for over 5 seconds, release (light should come on), release for 3 seconds, and press for another 5, and the codes should be reset.

Hey. I got around to taking a look at the diagnosis box today. I'm dismayed to say that i think it's been a victim of tampering. Only pins 3 and 6 existed, which on pin 2 I got 1-1-1, and on pin 6 I got 1-1-1. All the other pins had no contact point. You could see directly down to what is below the diagnosis box. Even if the jumper was put into the hole where the pin should be, the light wouldn't do anything. Is it possible to buy a new diagnosis box, or what do you recommend I do?
Thanks for the help,
Evan Piveral

um, that means the ABS on the 240 doesn't have the diagnostics, I guess. its normal for the other positions to be empty. pin 2 is your fuel injection and 6 is your ignition, 1-1-1 in both means they are AOK.

I do have the wiring diagrams for all year 240's on my other computer, I can look up to see if the 92 240 did/didn't have this when I get over there. I can't use these diagrams from my laptop due to enforced license restrictions on the $#@$#@$ VCOA disks.

Haha... thanks. I just found it strange that only port 2 and 6 had contacts in them. I still think that a rear sensor is needing cleaning, but can't find a way to clean it.

k, when I get to my other computer, I'll see if there's anything in the service literature about it (the VCOA DVD I have has /all/ the greenbooks (factory service manuals) for 240/260 series). our 240 doesn't have ABS, and I've never had to debug any problems with my 7s, 9s, or 850's ABS

Thanks... where does one get these manuals? Sound really handy!

the VCOA website, from the store, 'multimedia'. there's a disk for all 2xx, another for 7xx and yet another for 9xx, each is $65. the documents on these disks are heavily copy protected, so you can't screen copy pages from them, or print them to a PDF, and they can only be installed on one computer. you also can't access them on that computer via 'remote desktop' or VNC or any other method of remote computer screen sharing. since these 'greenbooks' would otherwise cost $100s bought seperately and many are no longer available in print at any cost, this is still a decent deal.

i've got them on my 'main' desktop system, but I broke my foot and have to keep it elevated, and I can't do that at my desk as the desk has a kick panel so I've been on my laptop all month.

Ouch. Hope the foot gets better soon! I'll look into the VCOA manuals. Currently I have a Bentley one, which has pretty much been doing a good job as a manual.

yeah, the bentley book is good for the basics, but it tends to blur the year by year variations together, and the wiring diagrams are nearly impossible to use.

So, my ABS light went off, however, I'm just concerned that it may have just burnt out. So, you know when you turn the key to start the car, well there's that moment when a majority of the indication lights come on. The ABS light doesn't come on then now. Should it?

yes, it should. its also possible the wire has been severed between the ABS controller (under the driver seat) and the dash. this wire runs into the transmission hump ona 740, I assume much the same on a 240 (haven't had a 240 w/ airbags)

IMHO, if you always wear your seatbelts, airbags are superfluous.

1992 940 gl
 

I'm not sure if I'm posting in the right place, but I'm new here so you will have to forgive me. My problem has to do with a couple of things. First off my abs and engine light are on. The diagnostic box is missing the test lead, button and led so it doesn't do me any good at all. I've looked at all sensors and they seem good, the wiring seems good. Is there a abs fuse somewhere I cant find? Does anyone know where I could find an old 92-93 940 or 960 to rob the box off? Any other ways to diagnois these things? Thanks in advance!....Scott

the diagnostic box is just a red LED, resistor or two and a pushbutton. the ECU and ICU each have one wire output that the jumper connects to. I believe the LED is connected to +12V via a resistor, and the pushbutton connects to ground