Brake Light Switch Changed - Still No Cruise - Please Help!

[frostybot1977]

Just changed the brake light switch to fix the cruise control, but it's done nothing except make me swear lots. I still get both cruise lights on (green) on switch on centre console, and amber (on dash) when i press the "set" button, but the speed just drops as soon you release the accelerator. I've tried it from 30mph up to 70mph and nothing. What's the next check?

Also, the car is auto so no clutch.

[marinabrian]

Originally Posted by frostybot1977

Just changed the brake light switch to fix the cruise control, but it's done nothing except make me swear lots. I still get both cruise lights on (green) on switch on centre console, and amber (on dash) when i press the "set" button, but the speed just drops as soon you release the accelerator. I've tried it from 30mph up to 70mph and nothing. What's the next check?

Also, the car is auto so no clutch.

As you have a V6, check the vacuum diaphragm on the throttle body isn't split, and actually holds a vacuum.

Also check the vacuum pipework, from the pump to the throttle body.

The fact you have the "motorway bridge" symbol on the dash, means the cruise ECU is seeing all of the electrical parameters correctly

Brian

[frostybot1977]

Originally Posted by marinabrian

As you have a V6, check the vacuum diaphragm on the throttle body isn't split, and actually holds a vacuum.

Also check the vacuum pipework, from the pump to the throttle body.

The fact you have the "motorway bridge" symbol on the dash, means the cruise ECU is seeing all of the electrical parameters correctly

Brian

Brilliant, thank you Off to buy a Haynes manual. Got rid of mine when I thought I wouldn't get another 75/ZT, 2 years ago