Question about 1998 Chevrolet Malibu

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What is a 5 Volt Reference Circuit ? this is a problem on my chevy malibu a 1998

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  • Chevrolet Master
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A reference circuit is a reduced voltage(less than 12) that is current controled
without it your car may suddenly accelerate smply by you turning
your heater or Ac on (the battery voltage changes )
it's used on many cars for the sensors like the throttle posisition
or Map
if the fault code says you lost it
you got a shorted wire or sensor somewhere on the engine

consult your vehicles engine wire diagram to see what sensors run on 5 volt ref
then start lookin and unhookin
(chiltons avail in most public librarys has a good wire diagram)

Posted on Jul 15, 2009

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  • Master
  • 1,615 Answers

12v and negative are supplied to the computer . Some components only need 5 vols. The computer will reduce the voltage to those components. Some components need 12 volts. Most of these are supplied directly from the battery to fuse block to relay or no relay and then to component. The computer has the ability to supply a modulated or constant ground as needed to all the components. If you lost the 5v reference you most likely need a PCM if the 12 and ground are good going to the PCM. Same for the grounds. If you lost the ground and the 12v is good coming from the fuse block.

Posted on Jul 15, 2009

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2007 cobaltpo651 circuit b how do i trll which is circuit b


DTC P0651: 5-Volt Reference 2 Circuit First off do you know what computer reference voltage is ? Your vehicle has 2 reference voltage circuits . This reference voltage is used to power engine sensors .
Diagnostic Fault Information
Circuit
Short to Ground
Open/High Resistance
Short to Voltage
Signal Performance
Accelerator Pedal Position (APP) Sensor 1 5-Volt Reference 2 Circuit
P0651
P2122
P0651
--
Accelerator Pedal Position (APP) Sensor 2 5-Volt Reference 1 Circuit
P0641
P2127
P0641
--
Air Conditioning (A/C) Refrigerant Pressure Sensor 5-Volt Reference 1 Circuit
P0641
P0532
P0641
--
Crankshaft Position Sensor 5-Volt Reference 2 Circuit
P0651
P0335
P0651
--
Fuel Tank Pressure (FTP) Sensor 5-Volt Reference 1 Circuit
P0641
P0452
P0641
--
Intake Camshaft Position Sensor 5-Volt Reference 1 Circuit
P0641
P0340
P0641
--
Manifold Absolute Pressure (MAP) Sensor 5-Volt Reference 1 Circuit
P0641
P0107
P0641
--
Secondary Air Injection (AIR) Solenoid 5-Volt Reference 2 Circuit
P0651, P2432
P2431
P0651, P2431
--
Throttle Position (TP) Sensor 1 5-Volt Reference 2 Circuit
P0651
P0122
P0651
--
Throttle Position (TP) Sensor 2 5-Volt Reference 2 Circuit
P0651
P0222
P0651
--

How to check the 5v reference circuit for short to ground Cadillac

Jun 10, 2017 | Cars & Trucks

2 Answers

03 chevy impala how to fix pocode 1635 is this the computer are what is it


DTC P1635
The powertrain control module (PCM) provides 5 volts to the following sensors:
?€¢
The manifold absolute pressure (MAP) sensor


?€¢
The exhaust gas recirculation (EGR) valve


?€¢
The fuel tank pressure (FTP) sensor


?€¢
The throttle position (TP) sensor

These 5-volt reference circuits are independent of each other outside the PCM, but are bussed together inside the PCM. Therefore a circuit condition on one sensor 5-volt reference circuit may affect the other sensor 5-volt reference circuits. The PCM monitors the voltage on the 5-volt reference circuit. If the PCM detects that the voltage is out of tolerance, DTC P1635 sets.
Diagnostic Aids
?€¢
If any sensor using a 5-volt bias voltage, such as the intake air temperature (IAT) sensor or fuel sensor, is shorted to voltage, DTC P1639 may set in addition to DTC P1635.


?€¢
For an intermittent condition, refer to Intermittent Conditions .


Does the vehicle start an run ?

Jun 11, 2015 | 2003 Chevrolet Impala

1 Answer

Chevy cobalt 2010 scan code po641 reduce engine power


Possible causes
- Faulty Engine Control Module (ECM)
- ECM harness is open or shorted
- ECM circuit poor electrical connection
- Shorted sensor on 5 volt circuit
help.jpg What does this mean? When is the code detected?
The Engine Control Module (ECM) has detected the sensor 5 volt reference circuit voltage is higher or lower than expected
Possible symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
P0641 Chevrolet Description
The control module has 2 internal 5-volt reference buses called "5-volt reference 1" and"5-volt reference 2". Each reference bus provided 5-volt reference circuit for more than one sensor. Therefore, a fault condition on one 5-volt reference circuit will affect the other 5-volt reference circuits connected to the reference bus. The control module monitors the voltage on the 5-volt reference buses.

Read more: http://engine-codes.com/p0641_chevrolet.html#ixzz31AP60YfR

Apr 19, 2014 | 2010 Chevrolet Cobalt

1 Answer

Chevy colorado


Hi there:

DTC P0641 - 5-Volt Reference 1 Circuit

DTC P0651 - 5-Volt Reference 2 Circuit

Diagnostic Fault Information
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Circuit/System Description
The engine control module (ECM) has 2 internal 5-volt reference busses called 5-volt reference 1 and 5-volt reference 2. Each reference bus provides 5-volt reference circuits for more than one sensor. Therefore, a fault condition on one 5-volt reference circuit will affect the other 5-volt reference circuits connected to that reference bus. The ECM monitors the voltage on the 5-volt reference busses.

The 5-volt reference 1 bus provides 5 volts to the following sensors:
* The manifold absolute pressure (MAP) sensor
* The fuel tank pressure (FTP) sensor
* The air conditioning (A/C) refrigerant pressure sensor
* The accelerator pedal position (APP) sensor 2
* The intake camshaft position (CMP) sensor

The 5-volt reference 2 bus provides 5 volts to the following sensors:
* The APP sensor 1
* The throttle position (TP) sensor 1 and 2
* The crankshaft position (CKP) sensor

Conditions for Running the DTC
* DTCs P0601, P0602, P0603, P0604, P0605, P0606, P0607, and P2610 are not set.
* The ignition is in Unlock, Accessory, Run, or Crank.
* The ignition voltage is more than 5.23 volts.
* DTCs P0641 and P0651 run continuously when the above conditions are met.

Conditions for Setting the DTC
The ECM detects a voltage out of tolerance condition on the 5-volt reference 1 or 2 bus for more than 0.5 second.

Action Taken When the DTC Sets
DTCs P0641 and P0651 are Type A DTCs.

Conditions for Clearing the MIL/DTC
DTCs P0641 and P0651 are Type A DTCs.

Diagnostic Aids
It may be possible to locate the fault by disconnecting one component at a time from the 5-volt reference circuit while viewing the 5-Volt Reference circuit parameter on the scan tool. The scan tool parameter would change from Fault to OK when the source of the fault is disconnected.

If all 5-volt reference components have been disconnected and a Fault is still indicated, the fault may exist in the wiring harness.

Circuit/System Verification
With the ignition ON and the engine OFF, observe the 5-volt Reference 1 and 2 parameters. The scan tool should display 4.3-4.7 volts for a normally operating system.

Circuit/System Testing
Important: Additional DTCs will set when disconnecting the components.

1. Ignition OFF, disconnect the harness connector of all appropriate sensors for the applicable DTC.

Important: A short to voltage on the signal circuit of certain components may cause this DTC to set.

2. Ignition ON, measure for 4.8-5.2 volts between one of the 5-volt reference circuits and ground.

* If the voltage is less than the specified value, test for a short to ground on all the 5-volt reference circuits. If all circuits test normal, replace the control module.
* If the voltage is greater than the specified value, test for a short to voltage on all the 5-volt reference circuits, or the signal circuit, for each component associated with the appropriate 5-volt reference circuit. If all circuits test normal, replace the control module.

3. Connect each component associated with the 5-volt reference circuit, one at a time, while monitoring the voltage. The voltage should not change more than 1 volt.

* If the voltage display changes more than the specified value when a component is connected, replace the component.


Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.

Thank you for using FixYa, have a nice day.

Jul 12, 2012 | Chevrolet Colorado Cars & Trucks

1 Answer

Code po 652


P0652 DODGE - 5 Volt Sensor Reference 2 Circuit Low
These 5-volt reference circuits are independent of each other outside the PCM, but are bussed together inside the Engine Control Module (ECM). Therefore a circuit condition on one sensor 5-volt reference circuit may affect the other sensor 5-volt reference circuits. The ECM monitors the voltage on the 5-volt reference circuit.

Possible causes
- Shorted sensor
- Shorted sensor circuit
- Failed ECM

When is the code detected? The ECM has detected an out of voltage range on the 5 volt reference circuit 2.

Hope helps.

Dec 02, 2011 | 2007 Dodge Sprinter

1 Answer

97 chevy malibu 3100 engine, what should the voltage be to the coolant tempture sendor be?


The ECT is a two wire sensor, a 5-volt reference signal is sent to the sensor and the signal return is based upon the change in the measured resistance due to temperature. The coorect way to test this sensor is by OHMs, not voltage. See the chart below.

ledsled378_124.jpg

Jun 09, 2011 | 1997 Chevrolet Malibu

1 Answer

I have a 2003 impala and its reading 5 volt reference voltage circuit condition. what do i need to fix this problem? The problem is causing my car to idle up to high. First the codes read that i needed...


all your sensors run off the 5 volt ref. so you will have to trace your wiring harness from the pcm\ecm all the way out under the hood to locate the broken or pinched wire.

Feb 26, 2010 | 1998 Chevrolet Malibu

2 Answers

P1635


P1635- 5 VOLT REFERENCE 1 CIRCUIT.
DESCRIPTION- the PCM uses the 5 v. reference 1 circuit to feed the throttle position sensor, MAP sensor EGR position sensor and the fuel tank pressure sensor with 5 volts. The engine computer monitors this voltage while the engine is running and will set the p1635 code if this 5 volt reference is out of its parameters.

Nov 09, 2009 | 2001 Chevrolet Malibu

1 Answer

1998 Malibu Instrument light not working


check the STOP- HAZ fuse with a 12 volt test ( both ends )

Apr 19, 2009 | 1998 Chevrolet Malibu

1 Answer

Problem with 1998 chevy malibu fog lights


hi disconnect your fog light switch if this doesn,t knock them off you need to find the fog lights relay and replace it as the fog light circuit is shorted best of luck yates210456

Oct 07, 2008 | 1998 Chevrolet Malibu

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