Why isn't my pcm showing the cause for a check brakes light when I run a diagnostic?

Speed Control The vehicle speed control system consists of the following components:

• speed control switches
• speed control deactivator switch
• stoplamp switch
• speed control indicator
• powertrain control module (PCM)
• electronic controlled throttle body (ECT)
• clockspring
• Principles of Operation
  The speed control system is controlled by the powertrain control module (PCM). The speed control system is designed to maintain a selected vehicle speed between 48 and 200 km/h (30 and 124 mph). The speed control system is controlled by the steering wheel mounted switch(es) (ON, OFF, SET+ [ACCEL], SET- [COAST], RESUME), and the brake pedal switches (stoplamp and speed control deactivator switches). The steering wheel mounted switch(es) are hardwired to the PCM through the clockspring.
  The speed control functions include:
  
  • turn on the speed control system
  • set and maintain the desired vehicle speed
  • accelerate the vehicle to a higher speed
  • coast down to a lower speed
  • tap-up/tap-down the vehicle speed
  • resume the prior vehicle speed
  • turn off the vehicle speed control system
  • Inspection and Verification
    
    1. Verify the customer concern.
    1. Visually inspect for obvious signs of mechanical or electrical damage.
    
    
    Visual Inspection Chart Mechanical Electrical
    • Throttle body
    • Central junction box (CJB) fuse 5 (7.5A)
    • Circuitry
    • Stoplamp switch
    • Speed control deactivator switch
    • Powertrain control module (PCM)
    • Speed control switches
    
    
    1. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
    1. Verify the speedometer operates correctly without speed control by test driving the vehicle. If the speedometer does not operate correctly, refer to Section 413-01 .
    1. Verify the parking brake warning indicator operates correctly. If the parking brake warning indicator does not operate correctly, refer to Section 413-01 .
    1. If the cause is not visually evident, connect the diagnostic tool to the data link connector and select the vehicle to be tested from the diagnostic tool menu. If the diagnostic tool does not communicate with the vehicle:
       • Check that the program card is correctly installed.
       • Check the connections to the vehicle.
       • Check the ignition switch position.
    1. If the diagnostic tool still does not communicate with the vehicle, refer to the diagnostic tool operating manual.
    1. Carry out the diagnostic tool data link test. If the diagnostic tool responds with:
       • CAN circuits fault; all electronic control units no response/not equipped, refer to Section 418-00 .
       • No response/not equipped for PCM, refer to Section 418-00 .
       • System passed, retrieve and record the continuous diagnostic trouble codes (DTCs), erase the continuous DTCs, and carry out the self-test diagnostics for the PCM.
    1. If the DTCs retrieved are related to the concern, go to the Powertrain Control Module (PCM) Diagnostic Trouble Code (DTC) Index.
    1. If no DTCs related to the concern are retrieved, GO to Symptom Chart . The PCM supply's a low voltage to the switches ,the switch is an input to the PCM . The PCM controls the electronic throttle control DC motor .
    2. Your best bet , take your vehicle to a qualified repair shop . Not a fuse problem . Having the vehicle checked for DTC'S - diagnostic trouble code would be the first step in the diagnostic procedure Powertrain Control Module (PCM) Diagnostic Trouble Code (DTC) Index DTCs Description Source Action P0500 Vehicle Speed Error PCM REFER to Section 307-01A or Section 307-01B . P0579 Cruise Control Multifunction Input A Circuit Range/Performance PCM Go To Pinpoint Test C . P0581 Cruise Control Multifunction Circuit High PCM Go To Pinpoint Test C . P0720 Insufficient Input from Output Shaft Speed Sensor PCM REFER to Section 307-01A or Section 307-01B . P0721 Noise Interference on Output Shaft Speed Sensor Signal PCM REFER to Section 307-01A or Section 307-01B . P1500 Vehicle Speed Sensor (VSS) Intermittent PCM REFER to Section 307-01A or Section 307-01B . P1501 Vehicle Speed Sensor (VSS) Out of Self-Test Range PCM REFER to Section 307-01A or Section 307-01B . P1572 Brake Pedal Switch Circuit PCM Go To Pinpoint Test B . P1703 Brake Switch Out of Self-Test Range PCM Go To Pinpoint Test B .

DTC P1554 Cruise Control Feedback Circuit
DTC P1689 Traction Control Delivered Torque Output Circuit
DTC P1860 TCC PWM Solenoid Circuit Electrical
Your best bet , take it to a qualified repair shop that knows how to diagnose DTC'S - diagnostic trouble code's , not just assume the part is bad . Code's have diagnostic trouble tree ,flow chart , to test electrical circuit's , not just replace part's . Changing a PCM would mean programming (dealer ) . Do yourself a favor an take it there .
Diagnostic Aids
An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation. Check for the following conditions:
• Misadjusted transaxle range switch.
Refer to Functional Test .
• Poor connection.
Inspect the PCM and PNP switch harness and connectors for improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
• Damaged harness.
Inspect the wiring harness for damage. If the harness appears to be OK, disconnect the transaxle range switch 7-way connector, turn ON the ignition switch and observe a voltmeter connected to the PNP circuit at the transaxle range switch 7-way harness connector while moving connectors and wiring harnesses related to the PNP switch. A change in voltage will indicate the location of the malfunction.
Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

Before replacing the PNP switch data on scan tool should have been done .
Put the vehicle in PARK.
Apply the parking brake.
Turn ON the ignition switch.
Observe Park/Neutral Position displayed on the scan tool.
Does the scan tool indicate that Park/Neutral is selected?

Put the vehicle in Neutral.
Observe Park/Neutral Position displayed on the scan tool.
Does the scan tool indicate that Park/Neutral is selected?
--
Go to Step 4
Go to Step 8
4
Observe Park/Neutral Position displayed on the scan tool while selecting D1, D2, D3, D4 and Reverse transaxle positions.
Does the scan tool indicate that park or neutral is selected in any of the above positions?

You have no clue as to what you are doing .

Do you have a check engine light on ? Is it cold when it runs good an then not when it warms up ? You need to have a diagnostic scan tool hooked up , check engine sensor data parameters .Have a pro diagnose it before replacing parts .ECT - engine coolant temp . sensor , mass air flow sensor , O2 sensors , also check fuel trims , if you know what those are . Fuel trims are a good diagnostic tool , is the PCM adding fuel for lean condition ., low fuel pressure ,plugged fuel filter , worn fuel pump etc... Or is the PCM subtracting fuel , leaking fuel injectors , bad fuel pressure regulator . What make , model an year vehicle ?

The ABS light will record a dtc, but not the brake warning light, which usually measures pressure differential front to back and fluid level.

P0300 is a Random Misfire
P0302 #2 Cylinder Misfire
U1120 The code U1120 means, lost wheel distance message. The powertrain control module(PCM) is not
receiving a signal from the anti-lock brake module. The problem could be a short in the bus circuit,
the PCM or the anti-lock brake module. This type of problem is best diagnosed by the dealer or a
local shop with the proper diagnostic scanning equipment. Hope this helps.

CHECK ALTERNATOR OUTPUT.MAKE YOUR VOLTAGE OUT PUT IS 13.5 TO 14.5 VOLTS.IF NOT ALTERNATOR BAD IF ALTERNATOR GOOD THE DEALERSHIP HAS TO HOOK CAR TO DIAGNOSTIC TO CHECK THE ENGINE PCM CONTROLS AND ABS BRAKES AND TRAC.SYSTEM.REASON I SAID ALTERNATOR BECAUSE I SEEN ALTERNATOR GO BAD UNTIL IT OUTPUT WAS LOW CAUSING CHECK ENGINE LIGHT AND ABS LIGHT TO COME ON.

First thing , knowing what all is involved in the cruise control system helps
Speed Control The speed control system is designed to maintain vehicle speed between 48 and 200 km/h (30 and 125 mph).
Normally, when the brake pedal is applied, the speed control module deactivates the speed control system. Under increased brake pedal effort, the deactivator switch, a normally closed switch, will open and remove power to the speed control actuator clutch, releasing the throttle independently of the speed control module.

Principles of Operation
The brake pedal position (BPP) switch is normally closed to ground. When the brake pedal is applied with the speed control system engaged, the BPP switch closes (to battery voltage), putting the speed control in stand-by mode.
NOTE: A redundant brake deactivator (BPA) switch is provided as an additional safety feature.
NOTE: The speed control module is integral to the powertrain control module (PCM).
The clockspring provides the electrical interface between the steering column wiring and the speed control switches in the steering wheel.
The inputs to the powertrain control module (PCM) required to operate the speed control system are the:

• anti-lock brake (ABS) module
• digital transmission range (TR) sensor
• speed control deactivator switch
• speed control switches
• vehicle speed signal (VSS)

The inputs to the speed control actuator come from the powertrain control module (PCM).
The outputs of the speed control actuator go to the speed control cable controlled throttle position sensor.

Special Tool(s) 73III Automotive Meter
105-R0057 or equivalent Worldwide Diagnostic System (WDS)
418-F224,

New Generation STAR (NGS) Tester
418-F052, or equivalent diagnostic tool with appropriate adapter cable
Inspection and Verification

1. Verify the customer concern.

1. Verify the speedometer operates correctly without using the speed control by test driving the vehicle. If the speedometer does not operate correctly, refer to Section 413-00 .

1. Verify the stoplamps operate correctly with the ignition switch in the OFF position. If the stoplamps do not operate correctly, refer to Section 417-01 .

1. Verify the parking brake is not applied and is operating correctly. If the parking brake is not operating correctly, refer to Section 206-00 .

1. Visually inspect for obvious signs of mechanical and electrical damage.

Visual Inspection Chart Mechanical Electrical

• Speed control cable
• Throttle lever
• Speed control actuator

• Battery junction box (BJB) fuse 40 (15A)
• Circuitry
• Powertrain control module (PCM)

1. If the concern remains after the inspection, connect the diagnostic tool to the data link connector (DLC) and select the vehicle to be tested from the diagnostic tool menu. If the diagnostic tool does not communicate with the vehicle:
   • check that the program card is correctly installed.
   • check the connections to the vehicle.
   • check the ignition switch position.

1. If the diagnostic tool still does not communicate with the vehicle, refer to the diagnostic tool operating manual.

1. Carry out the diagnostic tool data link test. If the diagnostic tool responds with:
   • SCP or ISO circuit fault; all electronic control units no response/not equipped, refer to Section 418-00 .
   • No response/not equipped for PCM, Go To Pinpoint Test A .
   • System passed, retrieve and record the continuous diagnostic trouble codes (DTCs), erase the continuous DTCs and carry out the KOEO Test.

1. If the DTCs retrieved are related to the concern, go to the Powertrain Control Module (PCM) Diagnostic Trouble Code (DTC) Index to continue diagnostics.

1. If no DTCs related to the concern are retrieved, proceed to the Symptom Chart to continue diagnostics.

NOTE: DTC P0703 and DTC P1572 must be repaired before any other DTC.

Powertrain Control Module (PCM) Diagnostic Trouble Code (DTC) Index DTCs Description Source Action P0500 Vehicle Speed Error PCM REFER to the Powertrain Control/Emissions Diagnosis (PC/ED) manual. P1565 Speed Control Command Switches High/Out of Range PCM Go To Pinpoint Test A . P1566 Speed Control Command Switches Low/Out of Range PCM Go To Pinpoint Test B . P1567 Speed Control Output Circuit PCM Go To Pinpoint Test C . P1568 Speed Control Unable to Hold Speed PCM Go To Pinpoint Test D . P1572 Brake On/Off Failure PCM Go To Pinpoint Test E . P0703 Brake Switch Input Malfunction PCM Go To Pinpoint Test E . IF thier are no codes go to the Symptom Chart

Symptom Chart Condition Possible Sources Action

• No communication with the powertrain control module (PCM)

• Battery junction box (BJB) fuse(s):
  • 11 (40A)
  • 40 (15A).
• Circuitry.
• PCM.

• REFER to Section 418-00 to continue communication diagnostics.

• The speed control switch is inoperative - no DTCs

• Speed control switch.

• INSTALL a new speed control switch. REFER to Speed Control Switch - With Remote Audio/Climate Controls or Speed Control Switch - Without Remote Audio/Climate Controls in this section.

• The speed control is inoperative - no DTCs

• Low battery voltage.
• Circuitry.
• Digital transmission range (TR) sensor (automatic transmission only).
• Parking brake switch.

• Go To Pinpoint Test F .

• The speed control indicator lamp is always on

• Circuitry.
• Instrument cluster.
• Powertrain control module (PCM).

• Go To Pinpoint Test G .

Your best bet , take it to a qualified repair shop . You have no idea how complex this is ?
Having a scan tool hooked up to check for DTC'S - diagnostic trouble codes should be the first step in the diagnostic procedure .
Powertrain Control Module (PCM) Diagnostic Trouble Code (DTC) Index DTCs Description Source Action P0500 Vehicle Speed Error PCM REFER to the Powertrain Control/Emissions Diagnosis (PC/ED) manual. P0579 Cruise Control Multifunction Input A Circuit Range/Performance PCM Go To Pinpoint Test C . P0581 Cruise Control Multifunction Circuit High PCM Go To Pinpoint Test C . P0833 Clutch Pedal Switch B Circuit PCM Go To Pinpoint Test D . P1572 Brake Pedal Switch Circuit PCM Go To Pinpoint Test B . P1703 Brake Switch Out of Self-Test Range PCM Go To Pinpoint Test B . All other DTCs - PCM REFER to the Powertrain Control/Emissions Diagnosis (PC/ED) manual to continue diagnosis.
Then reading up on how it works should be done .
Principles of Operation
The speed control system is controlled by the powertrain control module (PCM). The speed control system is designed to maintain a selected vehicle speed between 48 and 200 km/h (30 and 124 mph). The speed control system is controlled by the steering wheel mounted switches (ON, OFF, SET+, SET-, and RESUME), the stoplamp switch, clutch pedal speed control deactivator switch (manual transmission), and the speed control deactivator switch. The steering wheel mounted switches are hardwired to the PCM through the clockspring.
The speed control functions include:

• turning the speed control system on.
• setting and maintaining the desired vehicle speed.
• accelerating the vehicle speed.
• decelerating the vehicle speed.
• turning the vehicle speed control system off.
• cancelling the speed control.

Pressing and releasing the ON switch turns the speed control system on. Pressing and releasing the SET+ or SET- switch while the vehicle is traveling at the desired speed activates the speed control system.
Tapping the SET+ or the SET- switch while in the set mode increases or decreases the maintained vehicle speed by 1.6 km/h (1 mph) per tap, respectively. If either button is pressed and held, the vehicle speed continues to accelerate (SET+) or decelerate (SET-) until the button is released.
Pressing and releasing the OFF switch, or switching the ignition switch to the OFF position, turns the speed control system off. Applying the brake pedal puts the speed control system into the standby mode. Pressing the RESUME button when the speed control system is in the standby mode causes the vehicle to accelerate to the last set speed. RESUME does not function if the OFF button is pressed or if the current vehicle speed is below the minimum operational speed.
The clutch pedal speed control deactivator switch is used on vehicles equipped with a manual transmission. When the clutch pedal is applied with the vehicle speed control system engaged, the normally closed switch opens and signals the PCM to deactivate the speed control.
The speed control deactivator switch is provided as an additional safety feature. When the brake pedal is applied, an electrical signal from the stoplamp switch is sent to the smart junction box (SJB), which then sends a message to the PCM to deactivate the speed control system. Under increased brake pedal effort, the speed control deactivator switch opens and removes the voltage signal from the PCM input circuit, deactivating the speed control system.
Whenever the speed control system is engaged and active, a speed control icon on the instrument cluster is illuminated.
The inputs to the PCM are:

• Output shaft speed (OSS) sensor
• Transmission range (TR) sensor
• Speed control switch
• Clutch pedal speed control deactivator switch
• Speed control deactivator switch
• Accelerator pedal position sensor
• SJB
• Parking brake

The outputs of the PCM for the speed control system are:

• Speed control indicator lamp
• Throttle command

The speed control system throttle position is completely controlled by the PCM through the electronically controlled throttle body. Speed control electronics are contained entirely within the PCM.
When the speed control system is active, the PCM corrects for deviations in the actual vehicle speed by proportionally moving the throttle plate. The PCM modulates the throttle to minimize error between actual, and desired, vehicle speed.
The PCM strategy uses the throttle control for smooth accelerations.
The PCM sends a message over the controller area network (CAN) to the instrument cluster whenever the speed control telltale should be turned on or off.
In the event of an OFF command or a deactivation request from any source, the speed control system carries out a deactivation and immediately returns the throttle to the idle position.
The speed control system provides self-diagnostics. The speed control is disabled anytime an error is detected in the system. No cluster telltale or message center messages are displayed when faults occur. Fault codes are logged by the PCM.
An electronically controlled throttle system fault also causes the speed control system to be disabled and a warning telltale (wrench light) or a message center message is displayed.
Additionally, the following conditions cause the speed control system to deactivate:

• Transmission gear selector in a position other than D or OD (automatic transmission)
• Vehicle clutch pedal is applied
• Speed control set speed is over-ridden with the accelerator pedal for a period longer than 5 minutes
• Vehicle speed loss from set speed of greater than 16 km/h (10 mph) occurs
• Vehicle speed falls below the minimum allowable limit of 48 km/h (30 mph)
• Parking brake is applied
• Speed control switch is pressed or stuck for longer than 2 minutes

Inspection and Verification

1. Verify the customer concern.

1. Visually inspect the following for obvious signs of mechanical or electrical damage.

Visual Inspection Chart Mechanical Electrical

• Throttle body

• Smart junction box (SJB) fuse 18 (10A)
• Circuitry
• Speed control switch
• Clutch pedal speed control deactivator switch
• Speed control deactivator switch
• Stoplamp switch
• Powertrain control module (PCM)

1. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.

1. Verify the speedometer operates correctly without speed control by test driving the vehicle. If the speedometer does not operate correctly, refer to Section 413-01 .

1. Verify the stoplamps operate correctly with the ignition switch in the ON position. If the stoplamps do not operate correctly, refer to Section 417-01 .

1. Verify the parking brake warning indicator is operating correctly. If the parking brake warning indicator does not operate correctly, refer to Section 413-01 .

1. If the cause is not visually evident, connect the diagnostic tool to the data link connector (DLC) and select the vehicle to be tested from the diagnostic tool menu. If the diagnostic tool does not communicate with the vehicle:
   • check that the program card is correctly installed.
   • check the connections to the vehicle.
   • check the ignition switch position.

1. If the diagnostic tool still does not communicate with the vehicle, refer to the diagnostic tool operating manual.

1. Carry out the diagnostic tool data link test. If the diagnostic tool responds with:
   • CAN circuits fault; all electronic control units no response/not equipped, refer to Section 418-00 .
   • No response/not equipped for PCM, refer to Section 418-00 .
   • System passed, retrieve and record the continuous diagnostic trouble codes (DTCs), erase the continuous DTCs, and carry out the self-test diagnostics for the PCM.

1. If the DTCs retrieved are related to the concern, go to the Powertrain Control Module (PCM) Diagnostic Trouble Code (DTC) Index.

1. If no DTCs related to the concern are retrieved, GO to Symptom Chart .

P2299-BRAKE PEDAL POSITION / ACCELERATOR PEDAL POSITION INCOMPATIBLE

Set Condition:
The PCM recognizes a brake application following the APPS showing a fixed pedal opening. Temporary or permanent. Internally the PCM will reduce throttle opening below driver demand. One trip fault and the code will be set within 5 seconds. ETC light will illuminate, the light will only stay illuminated while DTC is active.




Possible Causes

DRIVER PRESSING ACCELERATOR PEDAL, THEN PRESSING BRAKE PEDAL, AND CONTINUES TO HOLD THEM DOWN SIMULTANEOUSLY

STOP LAMP SWITCH

APP SENSOR


The most likely cause of this DTC is Brake Torquing the engine by pressing the Accelerator pedal and the pressing the Brake Pedal.