would brake fail cause limp-home mode?
 

I was perusing a dashboard wiring diagram for my jalopy, and noticed that
the brake fail lamp connects not only to the master cylinder switch
and lamp check relay, but also to the ECU. Would this be so that the ECU
would limit the speed of the car if brakes died?

would brake fail cause limp-home mode?
 

On Saturday, January 27, 2018 at 4:36:10 PM UTC-10, wrote:
> I was perusing a dashboard wiring diagram for my jalopy, and noticed that
> the brake fail lamp connects not only to the master cylinder switch
> and lamp check relay, but also to the ECU. Would this be so that the ECU
> would limit the speed of the car if brakes died?

My guess is that the master cylinder sensor is connected to the ECU so that it can turn on the warning lamps. My guess is that the ECU turns on allor most of the warning lamps.

would brake fail cause limp-home mode?
 

On Sunday, January 28, 2018 at 11:02:44 AM UTC+8, dsi1 wrote:
>
> My guess is that the master cylinder sensor is connected to the ECU so that it can turn on the warning lamps. My guess is that the ECU turns on allor most of the warning lamps.

In this car the brake fail bulb is turned on directly by master cylinder switch.
The ECU only controls a few lamps like "engine", low fuel.

would brake fail cause limp-home mode?
 

On Saturday, January 27, 2018 at 6:21:23 PM UTC-10, wrote:
>
> In this car the brake fail bulb is turned on directly by master cylinder switch.
> The ECU only controls a few lamps like "engine", low fuel.

You could try disconnecting the master cylinder switch and forcing the light to come on and see if there's any speed capping. My guess is that the car companies don't want you to limp-home if your brake fails so no limp-home program is implemented when this occurs. Of course, what's the worst that could happen? I limped home when my brakes failed. Going over the mountain was scary!

would brake fail cause limp-home mode?
 

On Monday, January 29, 2018 at 8:40:46 AM UTC+8, dsi1 wrote:
>
> You could try disconnecting the master cylinder switch and forcing the light to come on and see if there's any speed capping. My guess is that the car companies don't want you to limp-home if your brake fails so no limp-home program is implemented when this occurs. Of course, what's the worst that could happen? I limped home when my brakes failed. Going over the mountain was scary!

I tried shorting the oil pressure switch, and it cut off the injectors,
i.e. stopped engine. So they don't want you to limp home with no oil in sump.