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2008 impala no tach signal to pcm

No tach signal reduce power light on with car not running code po 651

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DTC P0651: 5-Volt Reference 2 Circuit
You have a bad sensor or a short on the five ref. circuit .
The 5-volt reference 2 buss provides 5 volts to the following sensors:
The APP sensor 1

The crankshaft position (CKP) sensor

The throttle position (TP) sensor 1 and 2

The brake booster vacuum sensor

A bad sensor or short on the five volt ref. circuit will bring down the PCM and you will have a no start . I would pull the connectors off each of these sensors listed above to see if five volt ref. comes back to five volts . Well first check five volt ref at easiest sensor to get to . watch this video , he explains better !

2006 Cadillac DTS Shorted 5v Reference Circuit

Posted on Dec 05, 2016


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No tach signal 2008 impala

I told you before check 5 volt ref. if you can't , take it to a qualified repair shop . You probably shouldn't be trying to fix it anyway ,unless at least a dealer tech .

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What's the matter when a reduced engine power message comes on......2008 Impala"

Could be several things. General Motors PCM is programmed to limit engine power and acceleration, if there is a problem that could damage the engine . could be coolant failure , spark ignition problems etc. You will have to take it in and have it put on a reader to download the information from the pcm that was recorded during the problem.

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I have a 2008 Saturn outlook sometimes it will say traction control off and then says reduced engine power and it will viberate. You can shut it off and let it sit for a few minutes and start it back up...

What garage was it at ? Dealer reduced engine power means there is a problem with the electronic throttle control .this will shut off traction control off . Were there any DTC'S - diagnostic trouble codes read from the PCM - engine computer .
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Service Traction control / Engine power reduced/ Engine light on

Engine power reduced problem is the main culprit ! This has to do with the electronic throttle control system . Computer controlled throttle control . The Gas pedal assembly has position sensors as does the throttle body . These are inputs to the PCM/ECM - engine computer . By the signal from the gas pedal the PCM / ECM will control a DC electric motor on the throttle body ,opening an closing the throttle plate .When there is a problem with this system the check engine light comes on and the PCM/ECM will disable traction control an that light will be turned on etc..... These problems can be very tough to find . How much are you willing to spend to track down this problem . Need special tool's to find these problems . Electrical test scope (lab scope ) . Over time these parts wear an the PCM will see conflicting signals . Sometimes the part needs to wear out to find the problem . Have the repair shop keep the vehicle till they find the problem .
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2011 Chevy impala engine power reduced

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Runs rough,like a miss,changed fuel filter,injectors,no power when pushing on pedal????

It sounds to me that your Powertrain Control Module (PCM) is going into "Reduced Power Mode"(sometimes called "limp-in mode"). If the engine is running that bad or if the PCM is going into reduced power mode, the Check Engine light should be SCREAMING at you! If it is not, you probably need to do a "bulb check" to make sure the check engine light works.
There are several hundred things that can make the PCM do this. The ONLY way to find out which one is causing it at this time is to scan your computer network for fault codes and diagnose accordingly.

Please also review these articles:

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1 Answer

Engine light stays on 2008 impala after cleared takes 40 miles to come back on gas cap tried engine runs fine recently had oil change

The engine light is on due to a fault code that is recognized by the PCM. Bring your vehicle to a well supplied auto store; Autozone and the like, and ask them to read the DTC (diagnostic trouble code) that is stored in the PCM memory. They will perform this easy procedure free of charge.

Apr 16, 2011 | 2008 Chevrolet Impala

1 Answer

PO 341 code on 2002 chevy impala

This P0341 code basically means that the powertrain control module (PCM) detected a problem with the camshaft signal. The camshaft position sensor (CPS) sends a specific signal to the PCM for Top Dead Center on the compression stroke as well as signals indicating the position of the cam sensor. This is accomplished through a reluctor wheel attached to the camshaft that passes by the cam sensor. Any time that the signal to the PCM is inconsistent with what the signal should be, this code is set.
NOTE: this code can also be set by extended cranking periods.
Here is a possible solution to the problem;
  • Check that the wiring isn't routed too close to any secondary ignition components (coil, spark plug wires, etc.)
  • Visually inspect the wiring at the sensor for any burn marks, discoloration indicative of melting or chafing
  • Visually inspect the cam sensor for damage
  • Visually inspect the reluctor wheel through the cam sensor port (if possible) for any missing teeth or any damage
  • If reluctor isn't visible from outside the engine, visual test can only be done by removing cam shaft or intake manifold (depending on engine design)
  • If all checks out okay, then replace the sensor.

Be cool!!!!

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1 Answer

Have a po405 code on a 02 impala, said its a egr

In Hopes the info BELOW will Help, And Also the Mass Air Flow Sensor is A Totaly Different Sensor (MAF) The EGR Valve Code you are asking About is More Related to the Exhaust Gas that the EGR Valve is Allowing to Flow Past Its Self. I can tell you that From My Own Experience that EGR Valves Get Dirty More than they Fail and Require a Simple Removal and Cleaning of Carbon Buildup. This is after the Procedure Below is Performed.

The powertrain control module (PCM) monitors the exhaust gas recirculation (EGR) valve pintle position input to ensure that the valve responds properly to commands from the PCM and to detect a fault if the pintle position sensor circuit is open or shorted. If the PCM detect an excessively low EGR Position sensor signal voltage, this diagnostic trouble code (DTC) will set.

The system voltage is greater than 10 volts .

  • The EGR Position sensor is less than 0.14 volts at any time.
  • The condition is present for more than 20 seconds .
  • The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle in which the diagnostic runs and fails.
  • The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.
  • The PCM disables the EGR valve for the ignition cycle.

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4 Answers

Why does reduce engine power light comes on chevy

That is a hard problem to pin point without knowing what codes the computer has stored. It can be any number or sensors or engine problems.

You can go to most auto parts stores and they will pull the codes for you for free.

Jul 27, 2009 | 2005 Chevrolet Cobalt

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