Check engine code - P0719

[svracing]

Hello again,

I went to my local smog check, I hate CA, and the tech informed me that with a check engine light, it wouldn't pass. But was nice enough to check the code for me.

Came back as P0719. When I look it up it says "brake system - b circuit low".

Common problems are the brake switch.

My question - If the brake lights are working with no problem, can the switch still be causing the check engine light?

The brake fluid is near the minimum line, but still above it.

(As a side note, the cruise control is not engaging. Can these be related?)

[silverhairdeere]

what year , model , engine .

shd

[mudseeker]

Circuit Description
The brake switch indicates the brake pedal status. The brake switch is normally-closed. The brake switch supplies a B+ signal on circuit 420 to the VCM. The signal voltage circuit is opened when you apply the brakes. The VCM uses this signal in order to de-energize the TCC Sol. Valve when you apply the brakes.

When the VCM detects an open brake switch during accelerations, then Diagnostic Trouble Code (DTC) P0719 sets. DTC P0719 is a type B DTC.

Conditions for Setting the DTC
DTC P0719 sets if the following conditions occur two consecutive times:

• No VSS Assy. DTC P0502.
• The VCM detects an open brake switch or circuit (0 volts) for 15 minutes without going off for 2 seconds, and the following events occur seven consecutive times:
• The vehicle speed is less than 8 km/h (5 mph);
• then the vehicle speed is 832 km/h (5-20 mph) for 4 seconds;
• then the vehicle speed is greater than 32 km/h (20 mph) for 6 seconds.

Action Taken When the DTC Sets
The VCM illuminates the Malfunction Indicator Lamp (MIL).

Conditions for Clearing the MIL/DTC

• The VCM turns OFF the MIL after three consecutive ignition cycles without a failure reported.
• A scan tool can clear the DTC from the VCM history. The VCM clears the DTC from the VCM history if the vehicle completes 40 warm-up cycles without a failure reported.
• The VCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the VCM.

Diagnostic Aids

• Inspect the wiring for poor electrical connections at the VCM. Inspect the wiring for poor electrical connections at the brake switch. Look for the following conditions:
• A bent terminal.
• A backed out terminal.
• A damaged terminal.
• Poor terminal tension.
• A chafed wire.
• A broken wire inside the insulation.
• When diagnosing for an intermittent short or open condition, massage the wiring harness while watching the test equipment for a change.
• Ask about the customer's driving habits. Ask about unusual driving conditions (e.g. stop and go, expressway, etc.).
• Inspect the brake switch for proper mounting and adjustment.

[svracing]

Thanks for that info!

Brain **** on the info. 1996 GMC Sierra 1500. Not sure if it a P or K. Still trying to figure that out.

[crabtruck]

Wouldn't worry about the P or K thing too much, believe P for van, K for 4wd.
Do you have 4wd ? Not really important for this problem.

Gone are the days when brake pedal switches just opened and closed 1 circuit.
That's a double switch down there (see how many wires ?)
One set does brake lights etc, one does cruise control input (kills CC)
Sometimes referred to as TCC switch because of other jobs that switch does.

Was a recall on similiar years for miswired polarity of switch for nearby years.
Should not cause a problem like yours, usually no problem, then fire.

Seems like your symptoms show bad switch killing CC and setting code.
Use a test lamp and check switch before anything complicated.
Make sure you are getting results for BOTH parts of switch.
If that switch checks ok and you have a man trans, check clutch pedal switch.

This info was checked for accuracy but each time I read it
it said the same thing. Good luck.

[leolkfrm]

Here is a process

DTC P0719 Brake [COLOR=green! important][COLOR=green! important]Switch [COLOR=green! important]Circuit[/color][/color][/color] -- Low Input Step
Action
Value(s)
Yes
No

1
Was the Powertrain On-Board Diagnostic (OBD) System Check performed?
--
Go to Step 2
Go to

Powertrain On Board Diagnostic (OBD) System Check (4.3L)

Powertrain On Board Diagnostic (OBD) System Check (5.0L and 5.7L)

2
Install the scan tool (tech 1) �.
With the engine OFF, turn the [COLOR=green! important][COLOR=green! important]ignition [COLOR=green! important]switch[/color][/color][/color] to the RUN position.
Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and Failure Records for reference. The Clear Info function will erase the data.


Record the DTC Freeze Frame and Failure Records.
Select Brake Switch on the scan tool.
Disconnect the brake switch connector from the brake switch.
Install a fused jumper from terminal C to terminal D of the brake switch connector.
Did the brake switch status change from Open to Closed?
--
Go to Step 5
Go to Step 3

3
Remove the BRAKE fuse.
Inspect the fuse for an open.
Refer to Electrical Diagnosis, Section 8.

Was the fuse open?
--
Go to Step 4
Go to Step 6

4
Inspect circuit 441 for a short to ground.

Refer to Electrical Diagnosis, Section 8.

Did you find and correct a problem?
--
Go to Step 8
--

5
Replace the brake switch.

Refer to Brake Switch Replacement.

Is the replacement complete?
--
Go to Step 8
--

6
Inspect circuit 420 for an open.

Refer to Electrical Diagnosis, Section 8.

Did you find a problem?
--
Go to Step 8
Go to Step 7

7
Replace the VCM. Refer to Section 6:

VCM Replacement/Programming (4.3L)

VCM Replacement/Programming (5.0L and 5.7L)

Is the replacement complete?
--
Go to Step 8
--

8
In order to verify your repair, perform the following procedure:

Select DTC.
Select Clear Info.
Ensure that the following conditions are met:
- With the engine OFF, the [COLOR=green! important][COLOR=green! important]ignition [COLOR=green! important]switch[/color][/color][/color] is in the RUN position.

- The brake pedal is not depressed.

- The VCM brake switch signal indicates Closed (12 volts) for 2 seconds.

Select Specific DTC. Enter DTC P0719.
Has the test run and passed?
--
System OK
Begin the diagnosis again. Go to Step 1

[svracing]

FIXED!

Thank you all for the information. When I pulled the switch, I found a purple and orange wire that had worked loose.

The purple wire sends the signal that the brake is released and the orange wire is the always hot line. Th brake lights did work, so I figure I worked the orange line out when I pulled the switch.

As a side effect, the purple wire solved my cruise control issue.

Till next time!

[crabtruck]

Great news and thanks for posting back the fix.
You may have helped someone who has not even joined the forum yet !