CAUTION: RABS I vehicles which have been upgraded with RABS II anti-lock electronic control module will NOT have Keep Alive Memory and therefore will not be able to store codes when the vehicle is turned off.Section 06-09A: Brake System, Anti-Lock, Rear | 1996 F-150, F-250, F-350 Workshop Manual |
RABSI and RABSII refer to earlier and later versions of the Rear Anti-lock Brake System. A RABS I system that has previously been serviced may have its anti-lock electronic control module (2C018) upgraded to a RABS II. In the event of uncertainty whether the system has a RABS I or RABS II anti-lock electronic control module, the anti-lock electronic control module part number may be checked to determine the type of system.
CAUTION: RABS I vehicles which have been upgraded with RABS II anti-lock electronic control module will NOT have Keep Alive Memory and therefore will not be able to store codes when the vehicle is turned off.
| Model Year | RABS System |
|---|---|
| 87-92 | RABS I |
| 93 and Later | RABS II |
The Rear Anti-Lock Brake System (RABS II) continuously monitors rear wheel speed with a RABS sensor mounted in the rear axle housing (4010). When the teeth on a RABS sensor ring, mounted on the ring gear, pass the RABS sensor pole piece, an AC voltage is induced in the sensor circuit with a frequency and amplitude proportional to the average rear wheel speed. In the event of an impending lockup condition during braking, at vehicle speeds above approximately 8 km/h (5 mph), the anti-lock electronic control module modulates hydraulic pressure to the rear wheel cylinders (2261). This inhibits rear wheel lockup.