Tools.
The little bolts take a e-5 torx socket. I personally use a 5/32 and 4mm in addition to that, but you'll run into trouble if the bolt heads are corroded. I use a 3/8 ratcheting wrench with a 1/4" adapter. It gives you quite a bit more clearance, enough where you don't have to remove the MAF to Turbo hose on the 850's. Notice that my socket is wrapped with rubber tape, I do that as I don't tighten them back up with the wrench, I do it hand tight using just the socket. It's plenty.
The Harbor Freight e-5 socket won't work. It's too long. You may end up having to order one online, they're usually around $5.
Removal andInstallation
The car has to be off. You should also remove the ABS fuse. On the 850's it's in the fuse compartment in the cowl, on the 70 series it's in the separate fuse box above the module.
On the 850's, it's relatively easy. On the 96-98 turbo models, it helps to remove the MAF to Turbo air tube where it meets the MAF. This will give you just enough clearance. NA's are easier yet, there really isn't anything in the way.
On the 99-2001's there's less room to work with. It helps to remove the airbox, it's that tight.
MAKE SURE the socket is firmly seated on the head of the bolt. You don't want to rush it, or you risk stripping the head. You'll feel the bolt give, and from there you can loosen it with your fingers and the socket.
Don't overtighten the bolts when reinstalling it, it takes very little torque to hold it down. The large multi-pin connector doesn't always like to seat properly and I always tell people to reseat it several times to make a good connection. Make sure the smaller harness is completely bottomed out. At this point you will have to drive the car to clear your ABS and TRACS lights. There is no reprogramming needed, don't let a shop or mechanic tell you there is.
Here's a great video on how to do it. Not mine, but it's very good.
Stripped Bolt Heads.
These are no fun, but no need to overreact. Realistically, there's only one way to do it without destroying things, and that's using a Dremel with a small grinding bit. It helps to position a mirror to see what you are doing. DON'T use a sawzall, grinding wheel, hammer, etc. Harbor Freight sells their version of the Dremel for around $10 if you don't have one. Count on using one grinding bit per stripped bolt.
How do I know it's my module?
You can pay somebody to scan the car, or you can guess. On the 96-98 cars, 98% of the time it's the module. On the 99-2001's I'd peg it at 90% of the time. We'll touch on that next. IF your speedometer doesn't work, that's 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.
Vehicle issues
96 850's have a flimsy harness between the module and the ABS pump where the insulation rots off the wiring. Rubber tape or liquid tape does the trick.
99-2001 S80's. I personally despise these cars and avoid dealing with them. Some of them have numerous electrical issues, mainly involving the CEM. You can scan your codes and they will point to the module, but it may not be the problem.
Any car with a CEM/Can-bus and the 8619538 STC module. Same as above. Every car I've dealt with that has this combination has been a pure headache. The 8619538 module is soldered differently than the rest of the Teves Mark20 modules. They actually did this one right, I've never seen one that had any cracking around the pins on the board. For some reason, the other STC modules don't want to play right with a car with the 8619538 module. I don't know if it has to do with the CEM, I haven't been able to figure it out.
Blown Axle Boots. These will spew grease everywhere, and can foul up the wheel sensor.
Wheel sensors. If you think you have a sensor issue, it should test out between 900-1380 ohms.
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)
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.
2022 MARCH - SEE CORRECTIONS TO THIS SCHEMATIC BELOW, PIN11 is labelled incorrectly
Here is the schematic for a 98-2001
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 96-98 FWD cars, non-tracs. 850, V70, S70, C70 9140773 and 8602265
98 AWD cars. XC70, V70r, V70 AWD, S70 AWD. 9162675, 9140774 and 8602266
99-2001 FWD with STC. V70, S70, C70, S80 9472088, 9472401, 9472866, 9472971, 9496440, 9496946, 8619538
99-2001 FWD non-stc. V70, S70, C70, S80 9467582, 9472095, 9472969, 9496942, 9619535
99-2000 AWD cars. XC70, S70, V70. 8622093, 9472100, 9472650, 9496450
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.
Fixing your own module
There's already a huge thread on this, but I'll add one thing. DON'T use regular RTV/Silicone to put it back together. It really tears things up inside. GE Silicone II is non-acetic based, so it's safe to use and readily available. IF you choose to cut it open, don't go too deep, you'll cut off some resistors.
