Ever heard of 99 Astro which spins the starter everytime the gearshift is moved from D to neutral or park? Even does it when the engine is not running but the key is on. With the engine off, it just sounds like the starter is spinning to start. With the engine running (something I have found a way to avoid by turning it off before I shift from reverse to drive) it sounds really bad.
Am replacing the starter/solenoid tomorrow hoping that it's the solenoid. Seems the solenoid may be staying open all the time and when I pass thru P and N it spins. I replaced the starter relay without solving the problem. The last resort is the park/neutral switch if the new starter/solenoid does not correct the problem. Any other suggestions. Thanks
Lloyd

Probably not the starter or starter solenoid. The starter solenoid has two terminals on it, one has battery voltage to it all the time, the other terminal comes from the purple wire from neutral safety switch. The yellow wire on the neutral safety switch only has voltage when the ignition switch is in the START position and the transmission is in the PARK or NEUTRAL position. The neutral safety switch also controls the REVERSE lights which requires a circuit that is hot whenever the ignition switch is in the RUN position. It's possible that the neutral safety switch is applying battery voltage to the purple wire, (which goes to the starter solenoid) while moving the gearshift. If that's the case, the neutral safety switch needs to be replaced. Another possibility would be a malfunction in an add on remote start or security system. Hope this helps.

Thanks for the info. Kinda suspected it might be the park/neutral switch before I messed with the starter. I replaced the starter and now whenever I plug in the battery, I get a constant spinning of the pinion gear but no fly will action. Think I might have the three cables screwed up. I was careful when I disconnected them, but the repair manual shows the starter relay cable to the small terminal and the other two larger ones (battery and the other) connected to one terminal, the left one. I was sure that the two larger cables went one to one terminal and the other to the other. I broke the tip off the smaller one (starter relay) and have to replace it. Plan to hook it up tomorrow the way the bood shows with the two larger cables going to one terminal, the left one. Does this sound right? I bought the vehicle used last year and maybe someone replaced the starter and had it wired with each of the three cables going to each separate terninal. Thanks for your info about the p/n switch. really help with this problem.

There should be a 14ga purple wire going to the smaller stud on the solenoid. The larger stud should have a 4ga cable from the battery and a 10ga fusible link along with it.

If the starter runs when you connect the battery, it may be because the battery cable is connected to the braided wire on the starter motor or starter solenoid. The braided wire runs from the solenoid to the starter motor. The battery cable needs to be connected to the stud on the solenoid, not the braided wire, along with the fusible link.

Got the starter wired correctly and thanks for your help. You are also right about it not being the starter or solenoid. With the new starter wired correctly, it now start. I still have the original problem of the starter trying to engage for a second as I pass thru neutral and park. From park to reverse is fine, no engagement. From reverse to neutral, starter engagement and from drive to neutral, engagement. Have been turning key off as I shift so the starter does not engage with the engine running.
Going to put new neutral switch on tomorrow and if the problem is still there I would guess it might be a secondary security someone put on before I purchased the vehicle. Probable why the remote does not open the two front doors.
Really appreciate your help, thanks. Lloyd

The neutral safety switch might be okay. You just might find that if you remove the security system along with all of its components and wiring, the circuits might operate as they were designed to. One of the first things a good technician does when he's confronted with an electrical problem, is look for add-on accessories. Poor engineering, poor quality parts, and a poor installation job usually means trouble.

I think you are 100 percent right. I discovered today that the little red alarm light for the add on security has current to it even tho the horn, connections for the two front doors have been removed. Going to track where the alarm wiring goes to and see if I can determine the components that have been added on. Maybe at least I can completely disarm it. Ordered the ac/delco neutral switch and will be in Saturday. If I solve the problem before then will return unopend for a refund. It only cost $40 total and is an original part from GM. Will keep you posted and hoping I don't burn out something. Thanks again.
Lloyd

At last I found some of the problem. Located the security system someone had installed and took it out. Whoever installed it cut circuits and use lots of tape rather than doing it right. They installed a relay going up the steering column which I think is to the ignition because when I unplug, it will not start. So I left it plugged in for now. Also, a large plug-in with 3/4 wires going into it is unpluged and think it might be something with the front doors clicking but not locking when the keyless remote is used to lock or open all the doors. But, it now shifts thru neutral and park without engaging the starter.
Going to study the door wiring and see what I might do to get the front doors working with the remote.
Thanks again for the help.
Lloyd

You're on the right track now! Finding which track is always the hardest part. Tape, tap locks, and crimp connectors have no business in a vehicle. 60/40 lead/tin rosin core solder and heat shrink tube is the only way to go. Let me know how it goes. From the factory, the power door locks use two relays, one for lock and one for unlock.