I've been trying to figure out what's causing my brake light to stay lit on my idiot lights.

All my brake lights function and the ebrake clip/connector is hooked up...

The only thing not working is one side of the license plate lights...which has nothing to do with it.

Could it think my e-brake is engaged at all times? Idk what's wrong..I've swapped logicons thinking maybe it was just an error but it made no difference.

Rotary > Pistons

 

The warning light serves two functions. The other function would be low brake fluid in the Master Cylinder.

 

Did you hook up your brake sensor on the master?I know you just got your engine in.

 

its a little on the low side , ill fill it with some more fluid and see if it turns off.

the connector is plugged in

I took it for a few short drives so far and all is good but bac valve ground is shot so I.gotta trace that.

Rotary > Pistons

 

It runs to the ECU, pin 2G.

 

You should be able to test the circuit for the both the fluid sensor and ebrake by grounding the signal wiring going to either of the sensors.

The BAC gets constant 12v and the signal from the ecu is a momentary ground. There is no separate ground wire for it.

 

the ground or the power? I noticed the black wire has power on mine (the bigger wire), the voltage has varied from 11 volts to 13.

I've actually had to ground the wire to the block to make the bac turn on, I did that by cutting the harness and grounding it

Rotary > Pistons

 

well my bac won't function unless I ground it myself .. idk what's with it.

When I did that the rpms jumped and fluctuated from 1400-1600 when the engine was hot so the settings/calibration needs to be reset . Sonic rat has been helping me with alot of all this.

Rotary > Pistons

 

The B/W is voltage w/key to on. The other wire runs to the ECU and receives a ground pulse depending on how much load is placed on the engine such as turning on the A/C or braking and so on. Many times the wire will have close to twelve volts. When starting the car it would drop to a couple of volts to go full open so the BAC can assist in adding some air to the throttlebody to help start the car. It is not supposed to be grounded.

 

it is a duty cycle solenoid, duty solenoids aren't supposed to be fully grounded/open for more than a few seconds.

if your idle is too low you shouldn't be using the BAC as a fix for it, you can raise the idle with the idle set screw on the throttle body/BAC air bleed screw for turbo cars or the air bleed screw on top of the throttle body for non turbo cars. the engine should be able to idle with the BAC completely closed otherwise it will always have issues with wanting to stall when coming to curb idle(don't rely on the curb idle dashpot to function at this age of their lives, even when i adjust them they are too weak to function properly).

 

so why is my bac valve not working, is it the ecu or bac valve or what ?

I hope I didn't damage something in the ecu when I reversed the wires to the bac valve to see if maybe I rewired it backwards.

In any event its never worked, I don't know what the deal is with it and I'm trying to do what I can to fix it.

turning the screw on the bac also doesn't affect the idle in any way...

The car now idles just fine, coming to a stop its actually a tad bit high 1100 but it normally stays around 800 once it drops down from the electrical load etc.

The engine only has like 25 miles on it so as compression goes up things should get better...im just stumped at this bac valve.

I can test the voltage again at the ecu, maybe there is a break in the wire somewhere before it gets to the bac connector?

Or is it my bac itself is messed up, can I check its resistance to.see.if.its in spec?

Rotary > Pistons

 

if you ground the green wire and the idle goes up, the BAC is good, and its getting power like it should.

next step is to check the green wire to the ECU, and when that's fine, replace the ecu

 

Have you checked the voltage on the ECU wire when the engine is placed under load? If you measured the wire w/key to start you will see it drop considerably from 12 volts. And it will drop some when the A/C is turned on. In most situations the voltage change would be negligible and hard to decipher w/the voltmeter. If you had an instrument which measures duty cycles then you would have a better handle on things. One quick test results from turning the A/C on in addition to the headlights then unplug the two wire plug to the BAC and the engine will falter and want to die.

 

the ecu is an rtek 1.7 so I cant just replace it.

I'd rather suffer without the bac working I can't afford another ecu and ecu upgrade.

I'll check the voltage at 2g with the car.running

if it is the ecu ill just live with it until I can afford to get it fixed

Rotary > Pistons

 

the BAC will never work if the TPS isn't set or functioning properly.

if you set the TPS low enough with the car off you should hear it cycling with the key on. you can also check ground/duty cycle on the ECU wire to the BAC under the same situation.

but with your previous description of the car afternurning on decel i suspect your TPS is dead or wiring has issues, if it was working and set properly it would fuel cut on decel.

 

The TPS is fine, and has been checked a couple thousand times. I've been walking him through a long line of diagnostics to locate the issue. From faulty wiring/bad connectors/etc. The grounding was to see if the valve actually functioned and the connector was no longer an issue/etc. We had seen a proper duty cycle earlier, so the ECU should be fine. Now all that's left is verifying the duty cycle makes it to the connector pin and then diagnosing the other wire for issues.