Problem with Sprinter ABS..

I have problem with ABS brakes.. ABS light show. Code C1401 tell problem with abs relay. Where is relay? Sprinter is 313 -01

The relays are contained within the ABS pump module, which is the 'black box' mounted to the ABS pump, new ones range from £450-£600 here in the uk, there are various companies offering rebuilds on the net for around £150 or a secondhand replacement can be had for £50-£200. Make sure the module part number matches, (the part number is on the bottom of the module, it needs to be removed to see the label, unplug + 6 t20 torx head screws. Remember a new one will need 'coding', yours rebuilt will not, and providing numbers match and the doner van is the same spec a second hand one will not need coding. hope that helps!