I replaced my transmission in my 99 chevy silverado 1500 4X4. When I turn the key now it does nothing, I replaced the Park Neutral Safety Switch and still won't do anything. Everything is hooked up. Any suggestions?

Is it automatic or manual. If it's automatic try putting it in neutral and then starting it

There is no relay involved in the starter circuit of this vehicle . The micro switch you are talking about at the shifter has nothing to do with the starting circuiIt either . If you have a automatic transmission There is on the transmission the park neutral safety switch . Won't allow the vehicle to start unless the transmission is in park or neutral . Ford calls the switch manual lever position switch . Try moving the shift lever to netual to see if it starts .

Possible reverse light switch. Or park/neutral safety switch. What side of the case are the wires coming from?

It sounds like your transmission is not going into park. There is a safety switch which is why you have to engage the brake while the vehicle is in park to start it. It is not sending current thru because it is not registering that the vehicle is in park. Try engaging the emergency brake and taking the transmission to drive then back into park and see if it engages. Then try to turn the ignition and see if you have power to your gauges and ignition switch.

Test/Service/Replace

The circuit on newer cars with automatic transmissions has a neutral safety, or neutral start switch installed between the ignition switch and the starter. The ignition switch cannot operate the starter motor unless the transmission is in park or neutral.
Late model vehicles with manual transmissions have a starter/clutch interlock switch that requires the clutch to be depressed to the floor.
Neutral Safety Switch
Normal operations of a neutral safety switch provides a quick check for the adjustment of the gear selector linkage.

• To do this, move the selector slowly until it clicks into the PARK position.
• Turn the ignition key to the START position.
• If the starter operates, the PARK position is correct.
• After checking the PARK position, move the lever slowly toward the NEUTRAL position until the lever drops at the end of the NEUTRAL stop in the selector gate.
• If the starter also operates at this point, the gearshift linkage is properly adjusted.
• This quick test also tests the adjustment of the neutral safety switch.
• If the engine does not start in either or both of these positions, the neutral safety switch or the gear selector linkage needs adjustment or repair.

CAUTION
Since you must work under the vehicle to adjust most shift linkages make sure you properly raise and support the vehicle before working under it. Also, wear safety glasses or goggles while working under the vehicle.
A voltmeter can be used to check the switch for voltage when the ignition key is turned to the START position with the shift lever in PARK or NEUTRAL. If there is no voltage, the switch should be adjusted or replaced.

look under truck at transmission selector cable if it disconnected [because of rust ] or damaged --the lever may be in park but the selector at transmission is in gear wont start big problem with gm trucks burbs replaced may friends 05 silverado and had to do same for my 08 yukon

Then the problem is likely the ignition switch, or the neutral safety switch. Try jamming it into park a couple of times to see if it helps. If it does, you will need to change the neutral safety. If it doesnt, probably going to need an ignition switch. Those trucks, jimmys, and blazers are famous for ignition switch problems.

It could be the Neutral Safety Switch or Trans Range Switch located on the side of the trans where the shifter cable attaches. Check it and see if the wiring plug has been hot or deformed. I would have it checked first. Don't just go buy one and toss it on because I said to check it. I don't want you to waste money guessing.

sounds like the neutral safety switch. Hope this helps tim

In other words it won't start at all? The neutral safety switch may be faulty or a wire came off. It is located on the transmission.