A transmission control module for controlling an automatic transmission of a vehicle, the transmission control module comprising: a control circuit; and a memory electrically coupled to the control circuit and having stored therein a plurality of instructions, characterised in that the plurality of instructions, when executed by the control circuit, cause the control circuit to: determine a clutch hold pressure sufficient to lock an output shaft of the automatic transmission to resist roll-back of the vehicle as a function of a tractive effort of the vehicle; and apply the clutch hold pressure to at least one clutch of the automatic transmission as a function of a transmission output speed signal indicative of a rotational output speed of the automatic transmission, a throttle signal indicative of application of a throttle of the vehicle, and a brake signal indicative of application of a brake of the vehicle, compare the brake signal to a brake high threshold; compare (316, 318) the throttle signal to a throttle high threshold and a throttle medium threshold; set a clutch release ramp rate to a first ramp rate in response to the brake signal being less than the brake high threshold, and the throttle signal being greater than the throttle medium threshold and less than the throttle high threshold; and adjust the clutch hold pressure as a function of the current clutch hold pressure and the clutch release ramp rate. a control circuit; and a memory electrically coupled to the control circuit and having stored therein a plurality of instructions, characterised in that the plurality of instructions, when executed by the control circuit, cause the control circuit to: determine a clutch hold pressure sufficient to lock an output shaft of the automatic transmission to resist roll-back of the vehicle as a function of a tractive effort of the vehicle; and apply the clutch hold pressure to at least one clutch of the automatic transmission as a function of a transmission output speed signal indicative of a rotational output speed of the automatic transmission, a throttle signal indicative of application of a throttle of the vehicle, and a brake signal indicative of application of a brake of the vehicle, compare the brake signal to a brake high threshold; compare (316, 318) the throttle signal to a throttle high threshold and a throttle medium threshold; set a clutch release ramp rate to a first ramp rate in response to the brake signal being less than the brake high threshold, and the throttle signal being greater than the throttle medium threshold and less than the throttle high threshold; and adjust the clutch hold pressure as a function of the current clutch hold pressure and the clutch release ramp rate. determine a clutch hold pressure sufficient to lock an output shaft of the automatic transmission to resist roll-back of the vehicle as a function of a tractive effort of the vehicle; and apply the clutch hold pressure to at least one clutch of the automatic transmission as a function of a transmission output speed signal indicative of a rotational output speed of the automatic transmission, a throttle signal indicative of application of a throttle of the vehicle, and a brake signal indicative of application of a brake of the vehicle, compare the brake signal to a brake high threshold; a transmission output speed signal indicative of a rotational output speed of the automatic transmission, a throttle signal indicative of application of a throttle of the vehicle, and a brake signal indicative of application of a brake of the vehicle, compare the brake signal to a brake high threshold; compare (316, 318) the throttle signal to a throttle high threshold and a throttle medium threshold; set a clutch release ramp rate to a first ramp rate in response to the brake signal being less than the brake high threshold, and the throttle signal being greater than the throttle medium threshold and less than the throttle high threshold; and the brake signal being less than the brake high threshold, and the throttle signal being greater than the throttle medium threshold and less than the throttle high threshold; and adjust the clutch hold pressure as a function of the current clutch hold pressure and the clutch release ramp rate.