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Re: Problems starting
Sounds like you have a bad ground fault switch( safty switch). if you move the shifter around slightly while in park and have someone turn the switch will it start? that would indicate a short or a misalignment. Be sure to keep you foot on the brake anf have the parking brake set while trouble shooting. let me know MrRodneyLong@gmail.com
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Safety switch ? For what ? Park neutral safety switch ,is this what you mean ? Your vehicle not starting ? There is a lot more involved then just that switch.
For ignition switch power modes refer to Body Control System Description and Operation. Once the ignition is placed in the Run/Crank position, the control circuit of the Run/Crank relay is grounded by the body control module (BCM). With the Run/Crank relay switch closed, battery positive voltage flows through it and on to the park/neutral position (PNP) switch. With the PNP switch in either the Park or Neutral position, battery positive voltage will flow to the starter relay coil supply voltage input terminal of the powertrain control module and the coil side of the starter relay. Placing the ignition in the START position sends a message to the engine control module (ECM)/powertrain control module (PCM) requesting engine start. If the ECM/PCM has determined that the transmission is in Park or Neutral and theft is not active, it will ground the control circuit of the starter relay. Battery positive voltage will then flow through the switch side of the starter relay to the S terminal of the starter solenoid, cranking the engine. For remote vehicle start (RVS) information, refer to Keyless Entry System Description and Operation.
Is there a SECRUITY light lit on your instrument cluster ? Did you check the starter relay in the under hood fuse / relay center ?
For ignition switch power modes refer to Body Control System Description and Operation . Once the ignition is placed in the Run/Crank position, the control circuit of the Run/Crank relay is grounded by the body control module (BCM). With the Run/Crank relay switch closed, battery positive voltage flows through it and on to the park/neutral position (PNP) switch. With the PNP switch in either the Park or Neutral position, battery positive voltage will flow to the START relay coil supply voltage input terminal of the engine control module (ECM) and the coil side of the START relay. Placing the ignition in the START position sends a message to the ECM requesting engine start. If the ECM has determined that the transmission is in Park or Neutral and theft is not active, it will supply 12 volts to the control circuit of the START relay. Battery positive voltage will then flow through the switch side of the START relay to the S terminal of the starter solenoid, cranking the engine.
I suggest you take this to someone knowledgeable in new car electronics . There is a lot going on here , modules talking to each other on GMLAN serial data communication network . If no anti-theft system problems The BCM sends a message to the PCM on the GMLAN telling it to energize the run / crank relay ! If you knew vehicle systems you could check for power an control of the start relay right at the relay base / socket ! VEHICLE RELAYS Operation Diagnosis
A vehicle check engine light can come on for a variety of reasons. Many times your vehicle will run perfectly fine even with a sensor that is bad. You still want to get these fixed due to the fact that it can cause lower gas mileage or in time cause problems with your vehicle. If you go to Auto zone they can plug a computer into your car for free and tell you what is bad. Once those problems are fixed the same place can check your vehicle again and clear the check engine light.
It sounds as if your neutral safety start switch may be failing. This switch only allows for the safe start of an engine when the automatic transmission is in either park or neutral. It seems when you move around the gear selector you get it back to a spot where the switch allows the engine to start. Next time this happens while in park, try wiggling around the gear selector or place your foot on the brake (so you don't roll away) and place the transmission in to neutral. If it fires up you know to either adjust or replace the switch for the park position.
Take a look at the down shift cable and make sure its not broken especially were it connects to the throttle linkage.And maybe try cleaning the electrical plug that plugs into the trans.Its about a 7 to 9 wire plug.They tend to collect water and short the wiring out.
Mine only flashes when I start the engine. Once I place it in drive it stops and operates normally. This includes up and down shiftsing. If I place the tranny uner a load when the light is flashing (it flashes for about 10 secinds then it will chatter.
Maybe its a clogged transmission filter? Obviously is a fluid pressure problem. I drove it 5000 miles with this problem and it seems to not affected the tranny. Some folks talk about the Neutral Start switch. with 185K and a rebuilt tranny at 120K I am not going to invest $3000 to replace it