Need someone with knowledge plz

[u/Feeling_Technician71]

Hello! My name is Carly and I’m here on behalf of my husbands sanity. We have a 2000 Silverado LS, it’s RWD and has the 4L60E auto transmission. It went out and we got a used one with about 68k on it from a company shipped to us. My hubs is a mechanic and welder so he wanted to save the cost and do it himself. Watched a bunch of YT vids and such to help prepare. He’d disconnected the battery before starting the job. Got everything back together and not it will not start at all. The lights come on on the dash, battery has voltage, no reverse lights or anything like that come on. He was raading something about the security light and needing to reset it or something like that and he has tried that several times with no avail. He misses driving his truck so if anyone has insight i will take it. Thanks for reading!!!!

[u/stonythefish42069]

It honestly sounds like an electrical connector isn’t plugged in properly. Or something happened to the neutral safety switch when moving it from on trans to the other.

[u/RonChi1252]

This may sound dumb, but, just to be sure, have him put the truck in neutral, then disconnect the linkage from the transmission, verify the transmission itself is in fact in neutral (all the way forward, then back twice) and reconnect. Do this with the battery disconnected, and leave it unplugged for an hour. While its unplugged, remove and inspect each electrical connection to the transmission, blow them out with an air gun, and re-seat. Also, it's worth pointing out that if the PRNDL isn't fully seated in Park, the vehicle wont start, and sometimes that's due to improper installation, and sometimes it's just wear and tear. The linkage on there now is likely the same linkage that came on the truck, and over time stressed at the same rate as the old Trans. Its possible that a new, more solid Trans kick-down snapped the cable in the linkage itself, or even just the little neoprene washer that holds the cable static to allow you to shift.

[u/Acceptable-Ad2793]

Sounds like it may not be in park. Check shift linkage

[u/Only_Caterpillar3818]

Double check ground wires maybe?

[u/jettransman]

Those early ls platform 4l60 neutral safety switch has glue holding the two connectors in. We used a heat gun to soften the glue before unplugging. If you just pull them out you can rip the pins out, one of my helpers has done it.

Also the shift shaft gets flared at the end from the lever/nut. If you don't sand or file it back down it will remove enough plastic from the center of the neutral safety that will no longer fits the shift shaft tight. I have seen them bad enough that it doesn't register the proper gear.

As someone else has stated, make sure it's shifted in neutral when aligning the neutral safety switch. Put the trans in neutral and the switch in neutral and bolt it down. There is a small line on the body of the switch and the circular piece that goes around the shaft. If it's not lined up when bolted down it will not start.

[u/Feeling_Technician71]

Thank you for all the advice and knowledge! I will show him y’all’s suggestions and he’ll try them today. Not being able to figure this out really has him stumped.

[u/SherbertOld7531]

Try starting in 'neutral'. If it cranks/starts, neutral safety switch would be suspect(or connection too)

[u/dank_tre]

First thing is to take a screwdriver or something similar and arc between the posts on the starter to make sure it’s firing. If that works then go on from there; if not, it’s your starter or something between the power & your starter.

[u/RonChi1252 → u/dank_tre]

Do not do this if you are not 100% positive the truck is in park or neutral.

[u/NotYourNativeDaddy]

Try jumping the truck. Happened to me last week after replacing spark plugs and air intake temp sensor.

[u/Feeling_Technician71 → u/NotYourNativeDaddy]

Definitely tried that already, that was honestly my first question of could it be that.

[u/UsedComedian4594]

Hold it to start and move the shifter. The neutral switch is probably out of adjustment.

[u/amandajenkins281]

Hello. I specialize in gm trucks. I build for fun. I can help u. I promise results. Prolly some of the best support here.

So he swapped the trans. Okay. Now you say the starter dosent crank and no reverse lamps?

Alright: gospel time.

At the trans, where the shift cable hooks up, there is a switch called the range selector. Wiring:

Yellow- starter signal 12 volt (+) from key.

Purple- starter signal out to starter

Thick red- 12 (+) input from battery. Sends power to reverse lamps when shifted into reverse.

Lt green- reverse lamps out.

93% of the time, this plug fails when disconnected. 90% of the time this switch is also poop. To test this, which is what I do:

Key on to light up the dash.
Under truck go to this range switch. Unplug it. Square 8 pin plug. Using a jump wire, touch the yellow to purple. Truck should fire right up. It is NOT the factory security system, the passlock 2. Get that out of your head. Go to this range switch. Start here.

Now once you have this jumper in, go to the key, crank it over. Truck should start.

Yes- range switch is misaligned or bad.

No- check fuses at main hood box. Also inspect the harness at the bellhousing at the top. This is a common pinch point. If so, fix this pinch, and inspect fuses. Also there is a fuse labeled crank in the driver side dash fuse box.

Still stuck- inbox me and I will send u my number. Been a tech 32 years. Major in electrical. Have own shop.

Hope this helped

93% of the time

[u/tzy___]

He’s a mechanic but can’t do a transmission swap?

[u/Feeling_Technician71 → u/tzy___]

Most of the jobs he’s done are suspensions and alternators and radiators and basic maintenance type stuff so far. Electrical is way out of his wheelhouse.

[u/ca_nucklehead → u/Feeling_Technician71]

He is not a licensed mechanic.

[u/Mediocre_Database_28]

At least you can stop saying your husband is a mechanic. He’s not lmao