Midwest ABS Exchange and Repair
Specializing in Volvo ABS Modules and Repair.  Fast service and full support with a lifetime warranty-all at a reasonable price.
Troubleshooting.
+How do I know it's my module?

Volvo ABS module problems are very well known, almost all of them are going to have issues at some point.

You can pay somebody to scan the car, or you can guess. On the 96-2000 cars, 90% of the time it's the module.  We'll touch on that next. IF your speedometer doesn't work, that's typically a dead giveaway. Intermittent lights are usually a sign that the module is on it's way out. In time, they'll just stay on.  The big downside to paying for a scan is that the codes that come up are almost always wheel sensor codes which really don't fail very often.  That being said your mechanic my want to replace them when the reason that code is coming up is the fault of the module.  You'll also typically get a pump motor code which is along the same lines, the pump itself rarely fails, but the pins inside the module that control it do.  Communication codes are almost a dead giveaway that there's a module issue.

The normal sequence for a faulty module is intermittent ABS lights for a period of time, then they'll always be on, then in time the speedometer will drop out.  Most of this will tend to happen after the car is driven and the module gets hot.   If your ABS light suddenly came on one day and stayed on from that point on that typically is an external issue.  

It's important to remember that there are other parts of the ABS system, and like anything else problems do come up.  A lot of these cars are approaching 20 years on the road, based on that it is not uncommon at this point to have an issue in the system outside of the ABS module itself.  

AFTER INSTALLING.  All of my modules are road tested and cleared of codes before shipping.  The ABS/Traction lights should go off within 3 seconds of turning the key.  Always double check your large harness when installing, make sure it is 100% bottomed out and locked into place.  It DOES NOT always like to seat properly the first time due to the way it is designed.  

99 and later, the Check Engine Light and Flashing transmission light will not always go away on their own.  You have 1 option, have the codes cleared with a scanner....disconnecting the battery rarely clears the P0500, P1618 or P1633 codes or resets the transmission codes.  Realistically, any time your CEL is on, you should have it scanned to see why it is on, you can't guess.  Most common OBD readers will not read ABS or TCU codes.

Vehicle issues

1996-97 850

96-97 850's have a flimsy harness between the module and the ABS pump where the insulation rots off the wiring. Rubber/heavy electrical tape is needed to fix this.  If either of the bare wires touch each other or the aluminum ABS pump block, this will trigger the ABS lights.  Using a flathead screwdriver, pop the black cover off and then rewrap the wires individually with heavy electrical tape.  Some of the 96's also have faulty wiring going to the wheel sensors.  


S80

99-2001 S80's. I'm not a big fan of these cars and avoid dealing with them. Some of them have numerous electrical issues, mainly involving the CEM, the wiring harness or other electrical problems.  Not to mention problematic transmissions.  You can scan your codes and they will point to the module, but it may not be the problem especially if they are using the module with the 8619538 part number.  I've run into more than a few instances where the dealer will scan and say to replace the module, but the module in it works perfectly fine after testing it on another vehicle.



All Cars

The Fuse.  Always check your fuses first. 

Blown Axle Boots. These will spew grease everywhere, and can foul up the wheel sensor and tone ring on the axle.

Flashing service light.  The flashing service light (Not Check Engine light) is indicative of a instrument cluster problem.  If your speedometer is not working and that light is flashing the cluster can be involved.

P1618 Speed sensor code.  This is a TCU code.  It isn't always caused by the ABS module.  It can also be stubborn to clear with a common OBDII scanner.  Same thing for the P1633 and P0500 codes.

Loose Axle Nut.  This seems to come up quite a bit, after a front axle replacement the nut isn't torqued properly allowing the nut to come loose.  This allows the axle to move in and out of the front hub...in turn the tone ring and wheel sensor don't line up properly. 

Faulty ABS pump.  Easy to test with a meter.  You should get .5-5 ohms from it, testing at the small harness going to it.  Excessive resistance or an OL reading can indicate a faulty pump motor.  This rarely happens.  A pump motor code from the ABS module generally does not mean the pump motor is bad. 96-2000 pumps rarely fail, 2001 pumps will occasionally.

Alternator/Voltage issues.  This can be a tricky one to figure out, and you'll need a meter to do it.  Low voltage/high voltage output from the alternator or fluctuating voltage will cause the ABS lights to come on indicating various faults in the system.  The voltage issue tends to become more of an issue with the 8619538, 8619535 and some 8622093 modules. 99+ cars are more sensitive to voltage.

Ignition switch.  Another one that will cause ABS lights.  If manipulating the ignition key makes various warning lights on the cluster come and go or affect the headlights (dimming), that could be your problem.  

Wheel sensors. If you think you have a sensor issue, it should test out between 900-1380 ohms.  Always check the plug going into the wheel sensors.  They may not be plugged in all the way, they could be cracked or the wiring could be stressed. I've found that people that have recently had front end work done on their car routinely run into sensor problems.  Why?  People forget to unplug them, then when moving the steering knuckle out of the way they stress the connection.  They are located front and rear behind the brake rotor dust shield, and are held in place by one 10mm bolt.  I've also seen the wiring rub against the sway-bar end links, rubbing the insulation off down to bare wire.  Also, the wiring likes to fray where it enters the plug before the wheel sensor..almost always up front.  

Realistically, it doesn't hurt to pull them out and clean them occasionally.  If you're trying to troubleshoot them, you should pull them to check for debris and damage regardless even if the resistance tests out okay.  

To test the ABS wiring (from the sensors to the module) for an open circuit, put a multimeter on the following pins on the ABS module connector (not the module itself)
 . They should test out between 900-1380 ohms 

This only works for 1996-1998 models, not the 1999 and later cars.  On 99-2001 cars you can only test the sensor itself, not the continuity of the circuit.

LF sensor: pins 11 & 4

RF sensor: pins 18 & 3
LR sensor: pins 10 & 2
RR sensor: pins 17 & 1


Use your spare ABS module to figure out the location of the pins on the connector. Here's a picture for reference on a 96-98, all the pins are numbered.







Part numbers.


Volvo has a habit of giving one part several different part numbers. I'll list them here.

All 96-98 FWD cars with TRACS. 850, V70, S70, C70. 9162675, 9140774 and 8602266.  All of these are identical and compatible with each other.

All 96-98 FWD cars, non-tracs. 850, V70, S70, C70 9140773 and 8602265.  All of these are identical and compatible with each other.

98 AWD cars. XC70, V70r, V70 AWD, S70 AWD. 9162675, 9140774 and 8602266.  All of these are identical and compatible with each other.

99-2001 FWD with STC. V70, S70, C70, S80 9472088, 9472401, 9472866, 9472971, 9496440, 9496946, 8619538.  All of these are identical and compatible with each other.

99-2001 FWD non-stc. V70, S70, C70, S80 9467582, 9472095, 9472969, 9496942, 9619535.  All of these are identical and compatible with each other. 

99-2000 AWD cars. XC70, S70, V70. 8622093, 9472100, 9472650, 9496450.  All of these are identical and compatible with each other.


Junkyard/Used modules.


These are a crapshoot. You have a 50/50 chance of getting one that works. Some yards won't take them back either, because they're an electrical item. Don't pay more than $40 for a used one.

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