Help with ABS codes- 94 940 - Volvo Forums - Volvo Enthusiasts Forum

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Old 09-28-2005, 12:55 AM
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Default Help with ABS codes- 94 940

Need some help with 1994 940 ABS codes. I keep getting a 413 and and 411 code.
Usually after first starting off. Its intermittent and sometimes days can go by without a fault.
Then 3-4 in one day. Sometimes after a drive, I come to a stop and start off and on comes the light.
This happened today when the 411 code set. If I'm moving and switch the engine off/on
with the key the light goes out, ABS works (tested on wet pavement) and continues to
work until I stop, start moving then light comes back on. tonight after stopping several
times light did not come on. Seems like Volvo has intermittent connections sometimes.
Where is the ECU for the ABS on this vehicle?

Any ideas?
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Old 09-28-2005, 02:35 AM
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Location: Orlando, Florida
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Default RE: Help with ABS codes- 94 940

The ABS module should be under the hood by the unit.

I don't have my book home but if it is for the rear sensor check the wires good or you may have a bad sensor.
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Old 09-29-2005, 01:35 AM
Join Date: Feb 2005
Posts: 180
Default RE: Help with ABS codes- 94 940

How about a loose "Tone Ring" or Exciter ring? This is the toothed ring that the ABS wheel sensors read, one at each front wheel and one in the differential.

If these are loose (yes they come loose) the sensor will not read the pulses, so it will not know the wheel speed, and will set the code.

On another car (not a Volvo) I had a bad wheel bearing cause the ABS code, too much slop resulted in the sensor not reading the tone ring.

The wires to the wheel sensors can be damaged by road hazards, as well. Give it all a close look.

Finally, the connector to the rear differential sensor can become corroded if your car is in a saltly environment.


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Old 10-12-2005, 11:35 PM
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Default RE: Help with ABS codes- 94 940

More information.... More confusion.... Thoughts?
The other day I pulled off the ABS connector under the hood and to the ABS ECU. Also
tightened all grounds. Made numerous measurements on the ABS unit and all looks
OK according to the AllData manual I referenced. So I put it all back together backed
out car and damn, its on again.... Fast forward nearly two weeks... No failures...
Now this AM, back out of driveway, on it comes again. Left work for lunch with a
friend. It was chilly so I turned on the seat warmers. Started car, took off.... on
comes the ABS light. Now I'm pissed as it is acting up again. Left work tonight and
ran experiment.

Started car, seat warmers off, took off.... No ABS light
Stopped car, car still running, turned warmers on, took off.... On comes ABS light
Stopped car, stopped engine, turned warmers off, started engine, took off... No ABS light

European Autos STINK when it comes to electrical integrity. I've read that, see that here
and now I believe it.

It appears that either the ECU is very voltage sensitive and thus faults when the voltage
may be lower when the seat warmers are on, or there is a voltage drop to the ECU when
the seats are on.

Bad news is that I don't have a complete wiring diagram on the alldata site. Only partials
Anybody have access to a complete diagram they can email me for a 94 940 non turbo?
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Old 10-12-2005, 11:43 PM
Join Date: Feb 2005
Posts: 180
Default RE: Help with ABS codes- 94 940

OK : let me say for the record that I am JEALOUS that you have the seat warmers!


Since you seem to have covered the ABS computer grounds, now look at the seat warmer circuits! Is it one seat or both? (Probably the Driver's as that would see the most stress...
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Old 03-25-2007, 02:54 PM
Join Date: Mar 2007
Posts: 1
Default RE: Help with ABS codes- 94 940

im looking for a uk 940 se 2 litre turbo wiring diagram for abs as light does not come on

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Old 03-25-2007, 04:33 PM
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Location: Durham, England
Posts: 980
Default RE: Help with ABS codes- 94 940

You didn't say what year but this covers '91 - '95. I have also added a light check diagram in case the bulb/wiring is faulty.



Edit: Obviously it didn't like the wiring diagram so I have tried a different route.

And that one failed so here's another:

That worked. Hope it helps.

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1994, 2000, 740, 850, 940, abs, code, codes, exciter, fault, light, problem, read, ring, s80, volvo

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