97' 1500 5.7l will not start and brake light on

[rfelk]

1997 Chevrolet Silverado C1500 5.7 liter engine automatic

History: Changed out the intake manifold so several sensors were unplugged. Truck started fine and no error lights. When I shifted from park to reverse I noticed the transmission indicator light went out and also the vent fan stopped working. Drove truck for several minutes to reach operating temperature and everything seemed ok. Check for leaks and all good. Next time I tried to start it, the starter never engaged. The P,R,D,2,1, indicator light is off when key is in on position. They are illuminated when in accessory mode. Vent fan would not work. Brake light on and goes off when brake pedal is pressed.

Disconnected battery to reset computer. Truck worked fine and all was normal. Started truck multiple times, vent fan worked, and break light functioned normal. Drove for one day without problems, then the same problem occurred. Disconnecting battery did not change symptoms.

Current status is:

1) When key is in accessory, transmission light is on;
2) When key is in on mode, no status light. Can switch to other positions, but starter will never turn over and no draw on battery
3) Vent fan will not work.
4) Cycling power seemed to work once, but not currently.


Possible causes:

1) ECM is bad
2) transmission safety stop switch is bad
3) Wiring problem from manifold gasket replacement work is causing current issue.

Problem only started after I replaced the manifold gasket, so I somehow caused present problem.


Any recommendations or advice is appreciated!

[rfelk]

The problem is fixed. I moved grounding wires from the transmission mounting bolt to one on the engine block. Also found the grounding wire that is mounted on the front of the engine was loose.

Truck is operating fine now.

[j cAT]

Originally Posted by rfelk

The problem is fixed. I moved grounding wires from the transmission mounting bolt to one on the engine block. Also found the grounding wire that is mounted on the front of the engine was loose.

Truck is operating fine now.

you are lucky that the ecm was not damaged. i prefer to use the engine as a ground . this is because as vehicle ages this reduces the effectivness of frame to provide a good ground.

[777stickman]

Great job describing the problem and another great job of posting what fixed it.