1996 854 ABS light, instrument lighting

Teddy1975 · Post by **Teddy1975** » 06 Jan 2016, 12:33

This is my first post on this board so I hope you'll treat me kindly.

I've been trying to find information regarding some issues I have with my recent purchase, a Volvo 850, 1996 model. It's the 2.0 liters, 126BHP non-turbo version. Unfortunately my search has left me with more questions than answers and quite frustrated.

First issue, the ABS light is lit at all times and service light is lit at start and shuts off after about 20 seconds. I want to read the OBD codes and reset the ABS and service lights. I've already tried two different OBD2 tools, which failed to communicate with the car, even though one of them claims to be able to read the ISO 9141-2 protocol that I believe the 850 use? I've even tried to make a blink-out tool, using the LED push-button approach, but no luck here either (connected plus side of 12v LED to pin 16, negative to pin 5 and via push button to pin 12, supposedly ABS?)... So I'm at a wits end now. I have read about the VOL-FCR program, but before I try that approach, I wanted to hear if anyone has gotten this to work with a '96 850 and what cable to use?

Second issue, the backlight in the LCD with the info center (clock/outside temp) does not work at all and two of the illumination lights in the dash are flickering on/off, one on the far left behind the gas meter and the other behind the rev counter. If I turn the illumination light all the way down, the flickering stops, but then I can't see how fast I'm driving etc. Could this be a bad connection in the light switch with an easy fix, or is it something more serious? There is also no light in any of the dial arms (gas/water temp/speedo/rev), is this normal and if so, any way to get them light up?

I have a couple more questions, but those aren't as important as those mentioned here. Especially the ABS, since I can't get license plates for the car until that is fixed. I am on a really tight budget and even if it would be much simpler just handing the car over to a Volvo garage, this isn't an option for me.

Thanks for any and all help,
Teddy

Post by **Ozark Lee** » 06 Jan 2016, 21:21

Greetings,

A typical OBD-II scanner won't read ABS codes at all, it takes a scanner equipped to interrogate the system specifically. There are some scanners that will read the ABS but they are on the upper end of the price range. Typically with the Volvo ABS system a reset won't do a thing for you anyway. Starting int he '96 model year (perhaps as early as '95 in Europe) the ABS system was changed and sadly the upgraded version has a failure rate that approaches 100%. The failures almost aways due to a manufacturing process flaw rather than actual component failures. If you are handy at soldering you can repair the module yourself but if that is not a part of your skill set then they can be rebuilt for a reasonable price. I'm not sure where to steer you to in Denmark to get the module rebuilt though. We have an outstanding rebuilder that is a member here and I think he can deal with international service but I don't know that for sure. He has a website here and you can contact him through the site to see what he can do for you:

https://www.midwest-abs.com/ABS_Modules.php

If you are handy with a soldering iron here is how I rebuilt mine:

https://www.matthewsvolvosite.com/forums ... hp?t=12651

The system is self resetting and once the module is repaired or replaced it will go through a self test and the light will go out after a couple of hundred feet of travel.

The service light is just a nuisance light to remind you to change the oil but it takes a special reset tool to turn it off. The VOL-FCR with a VAG-COM cable will reset it and it will also interrogate many of the other proprietary Volvo systems. What it typically will not read is the engine codes but your standard OBD-II scanner should read those. You can also build a scanner with an ELM327 chip and use a terminal program to interrogate the subsystems but it isn't user friendly unless you are used to terminal commands like you would use on an old dial up modem. There are a couple of more user friendly freeware programs floating around that make using the ELM327 a bit less intimidating and you can do things with that chip that you can't do with the VOl-FCR program. The ELM327 cable is a great tool but it takes a bit more to use it than most.

From your description of the instrument cluster light problems it sounds like you have a bad dimmer and some burned out lamps. The dimmer gets dirty, like a scratchy volume control, and the lights flicker like you describe. In some cases you can use spray electrical contact cleaner to clean up the dimmer and it will go back to working. Failing that, the only cure is to either replace the dimmer switch or just hard wire the lights to their brightest setting. The fix for the clock/temp gauge is to replace the lamps and I would suggest that you re-lamp the entire cluster while it is out. The lone exception to that is the service light which I take out and stomp on. The service lamp should not be confused with the check engine light but I think your car has the Lambda light instead of a check engine light. They are the same thing but in the US they are all the "Check Engine" light. That light is important.

If those are the only issues you have you have done quite well. The 850s are great cars but they have some issues, the ABS is one of them. The good news is that the issues that they do have are all pretty much the same on all of them and message boards like this one can get you through about any problem you might encounter.

...Lee

Teddy1975 · Post by **Teddy1975** » 07 Jan 2016, 12:28

Thank you for your reply Lee.

I did some more tests today, figured I might as well try to check the ABS sensors since the terminals are so easily accessible. Unfortunately they all measured from 996-1012 ohms, which from my understanding is well within the tresholds.

I went ahead and did the rebuild of the module, the soldering job done on it wasn't so bad however, and it didn't fix the problem. I checked the wiring to the ABS pump motor, having read that it could be a problem with shearing/shorting, but the rubber is solid and still flexible. Hard to believe it is 20 years old.

So far I've done the following:
1. Check ABS control module (Resoldered, plugs sprayed with WD-40) - Seems ok.
2. Check wiring between module and pump motor. Cable is in mint condition, no cracks or missing insulation.
3. Check wheel sensor readings (all 4 checks out).

So next thing I can check is either the brake pedal sensor (no clue how to check that, without OBD readout) or the ABS pump motor. Is there an easy way to see if the pump is working, like hooking it up to the battery and listen/feel for activation or measure resistance on the power cables?

I test drove the car after I checked the sensors and the ABS is clearly not working at all. On ice/snow all wheels blocked pretty much as soon as I hit the brake.

Apart from the ABS problems and the rather minor issues with lack of/flickering lights in the instrument cluster and dome/floor lights, I am really pleased with the car, considering I only paid $580 for it. I just hope the ABS problem won't cost me another $500 or more to fix.

/Teddy

Teddy1975 · Post by **Teddy1975** » 07 Jan 2016, 13:52

Well, I tried to check the ABS pump motor. It made a lot of noise when I hooked it up to the battery, in fact it's so loud that I can hear it over the engine when inside the car.

So I'm guessing the pump is not working properly due to the noise it makes, a really loud whirring noise?

Post by **Ozark Lee** » 07 Jan 2016, 22:09

Teddy1975 wrote:Well, I tried to check the ABS pump motor. It made a lot of noise when I hooked it up to the battery, in fact it's so loud that I can hear it over the engine when inside the car.

So I'm guessing the pump is not working properly due to the noise it makes, a really loud whirring noise?

Actually that is typical of what it should sound like. Usually when they are bad they either do nothing at all or hum and the motor gets very hot, very quickly.

You sound quite competent when it comes to electrical troubleshooting so the factory manual might be a great resource for you. The manual lays out some step by step troubleshooting instructions but many of the tests reference a proprietary breakout box to make measurements. You can do the same measurements with out the breakout box by penetrating the insulation on the wires or back probing the connectors.

The diagnostic procedures are in this manual:

https://www.matthewsvolvosite.com/downlo ... vo_850.zip

...Lee

Teddy1975 · Post by **Teddy1975** » 08 Jan 2016, 09:10

Thanks again Lee.

I was getting worried when I had a look at what pick'n'pays want for the hydryalic pump unit so now that I know the pump is ok, I can probably sleep a little easier tonight.

I've ordered a cheap vag com cable on Ebay, hoping that I can get it to work with VOL-FCR and have it tell me that it's a simple thing, like one of the wheel ABS rings that's broken. I can't inspect it visually for the moment as we just got 7" more snow today and I have no access to a heated garage. So for now, I'll focus on putting together a to-do list of all the things I need to do in order to keep the car running for another 10 years at least. I'll create other threads for the other questions I have.

/Teddy

PeteB · Post by **PeteB** » 08 Jan 2016, 17:40

Nice work, I'm working on ours today and tomorrow also.
I've only found deep sockets in the E5 type and it is difficult to get to the bottom
bolts. Going to try with extra lighting tomorrow. Or might look for a better
socket.

PeteB · Post by **PeteB** » 08 Jan 2016, 17:50

Just thought I'd mention that you really have to look over the whole board
for broken/cold joints. I've not done it yet but a broken connection to a diode
is shown here for example:

I'm probably going to send ours out just to keep it simple.

Teddy1975 · Post by **Teddy1975** » 08 Jan 2016, 19:00

Hi Pete.

I was lucky that one of my socket wrench sets had all the E type sockets in it, so I didn't have to buy the E5 for the removal of the module, plus it's a slim one. The socket I have is a 1/4" and I put it on a 1/4" to ½" converter.

This worked really well and I only had to remove the aluminum hose from the exhaust to the air filter box to get enough space to remove and reinstall the module. No bent fingers or scraped knuckles

I'll try removing the module and redo all the soldering on it, not just the "trouble" spots. I have a Weller adjustable heat soldering iron with an assortment of tips, so it's just a matter of taking the time to do it.

Thank you for the tip!

Post by **Matty Moo** » 08 Jan 2016, 21:14

I'm assuming you soldered all of the pins on that side of the board and flowed them all correctly.

When you get vol-fcr running clear all the codes, then drive and see what they say.