95 tahoe, service engine soon light comes on & shift points off

service engine soon ??? This has to do with the vehicles emissions When this light comes on it means your vehicle is polluting 1 & 1/2 times greater then the EPA allows . DTC'S - diagnostic trouble codes are stored in the engine computer . The light is a warning to the driver to take your vehicle to a qualified repair shop.

The service engine soon light should go on when there is a hard code set in the computer.

One can use an OBD-II Scanner in vehicles made in 1996 or later to 'erase code' but if there is a problem in the engine, the computer will come up with a hard code immediately.

Only, with intermittent codes can the 'erase code' button get rid of the light for any length of time.

Also, if there is no service engine soon light at all (ignition on before starting), then the ECM (Electronic Control Module) or PCM (Powertrain Control Module) is bad.

Similarly, I if the l ight goes on but there is no code stored, that might point to a PCM problem existing where the PCM should be replaced to get rid of the light.
---
Also, the problem with getting it out of Park to Reverse or Drive is usually a bad brake switch which sends a signal to unlock the shifter when the brake pedal is depressed. This is a separate issue.

I wish you luck on these repairs.

It has to be done with a code reader,the codes have to be erased,but it will come back on if the problem is still there,auto zone can do this for you for free.

that is a heated O2 sensor code

If there is an Auto Zone or any other large auto parts store, have them scan the truck for the DTC codes. The DTC codes will identify the Issues that needs to be addressed in your engine and transmission that has set off the service engine light on. Once the issues has been resolved, the light will reset it self after the third start up and after 40 start up will erase it self from the history as long as there is no additional issues. Good luck and hope this helps, Shift suddenly become very hard. When going from park to either reverse or drive it slams into gear. 1-2 and 2-3 shifts are also harsh. All gears seems to work. Problem may be intermittent: Check TPS for smooth electrical response. If the response is jumpy or erratic at all, replace TPS.

Take it to you local parts store and have them see what codes are making the light come on. Then you go from there.


Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/sean_54c3a3dc48a7773c

If you can give me the codes I can help you out with the problem.

it might be your vehicle speed sensor. It affects your speedometer, your cruise control and your trans shift points. Also, your throttle position sensor (TPS) affects shift points.

mine had the same intermittent code it was my o2 sensor

I used to live on a farm where we had a number of Chevy diesel's in the 90-98 year range. The 6.2 and 6.5L diesel's in those trucks were known to have problems. A very common problem was with the fuel injection pump going bad, causing the engine to intermittently stall for apparently no reason during driving.