3 months ago I installed a new battery in my 1989 GMC Sierra and the battery warning light came on. It was not on before. It stated OK then.,but after setting for 3 months the battery was dead and has a bad cell. Why did the battery light come on and why did the battery go bad.

Yes it is a throttle body injection,looks very similar to an older style carburetor,warning! Do not turn ignition key on during removal of injectors,remove negative battery cable before removal,lightly coat rubber orings with petroleum jelly before installation.

when replacing coolant, did you bleed the air from system! you can remove radiator or overflow cap when cold. start vehicle and let it run until thermostat opens,when all air is out hoses should get hot. but before starting, turn heater on to high setting, if you vehicle does not have a air bleeder on it. do as above. just be sure radiator is full of coolant. after hoses get hot, turn off heater, then put cap back on radiator or overflow. good-day! the first thing to do is to check for a stuck closed thermostat. do this first ok!

code p 0654 refers to engine rpm output--circuit malfunction ===causes wiring ---ECM
code p 0650 refers to malfunction indicator lamp(MIL)--circuit malfunction====causes wiring --MIL---ECm
also refers to crankshaft position/cam shaft position sensor bank 1 sensor A --correlation===causes wiring---CKP sensor ---CMP sensor--mechanical fault

I wouldn't eliminate the battery, but suspect a fuel pump,if it is ten years old

hi, i have seen this problem ten years ago twice, but i was dumbfounded by the answer. all details aside, I replaced the ecm, and never had the problem again with both of them. this repair was a recommended repair by the local truck depot in my town, they stated the ecm got hot along with the truck and it lost the injector sensor signal. now, don't take this solution and run with it, i haven't repaired a 6.2 diesel in ten years and i maybe off track completely. but at least maybe you could ask around your town or maybe a large truck facility about this. of course, you should take to a shop to have diagnosed. hope i could help.

Use this guide to help you find the color
https://www.duplicolor.com/color_selection.pdf

u can do the check the other way around/ disconnect the fuel line that supply the injectors/ put the pipe in a small plastic container to see if fuel is being supplied by the pump and avoid fuel spill in ur engine/ crank the engine for at least 5 seconds see if the fuel squirts with pressure/ if it does then ur fuel pump is ok / blockage is somewhere down the fuel line/ u can check fuel lines by blowing it with air but u gonna need the help of an air compressor.....

Use a test light and check the power to the coil, I believe it's marked battery. If you have power going to the coil and no spark you will have to replace the coil.

make sure your geetin 12v to brake switch if not jumper a wire then try it

dis-connect negative battery cable
the brake lite switch is located on the top of the brake pedal
unplug the electrical connection and pull the switch off of the pedal
to re-install reverse these steps