Chevy S-10 Transmission Still Shifting Wrong

Question:
Before I had the trans replaced, it went into what I believe is a safety mode- only 1 or 2 gears would operate. (it had run fine with no problems for 240K miles) However after having put in a new unit, the same thing happened. 1993 Chevy S-10 blazer Vortec 4.3L. Replaced transmission w/rebuilt.

Have now sent it back to the transmission shop 6 times. Each time they would return it, after driving about 150 miles, the same thing happened. The shop claims there is a short in the wiring somewhere and a fuse is blowing, but as of now, they have been unable to find the problem. Any other ideas?

Answer:
Yes, this does sound like a blown fuse. It most likely is one that sends power down to the transmission to feed the internal shift solenoids. You may also have codes stored in the computer- with or without a check engine light. Most of the large national parts store chains will scan the computer for free. Codes for shift solenoids may be stored. When there is a loss of power feed to the trans, it does go into a default shift mode. Check all the fuses in the dash fuse box and the underhood fuse box- if it has one. Replace any blown fuses. Now to find out where the short is can get pretty involved. There are a few placed that are common.

1. The large wiring harness that goes over and near the power brake booster in the drivers side firewall under the hood.

2. Following that harness to the back side of the engine as it starts to go down to the transmission connector.

3. The ignition switch wiring harness under the dash that runs down the steering column and into the firewall.

4. Or anywhere in between these locations. Best way to find it is to install a circuit in place of the blown fuse, turn the key on- engine off, and pull on these harness locations while listening for the circuit breaker to pop. That will tell you where the short is. Then you would need to get into the wiring harness at that location and check each wire for being rubbed through on something metal. It will most likely be a pink wire.

If you do not have a circuit breaker, then installing a good fuse and doing the same. Have someone get close to the fuse while you are doing this and listen for the fuse to pop.

Question:
When I turn my truck on or put it in gear the reverse lights are on even in drive...How do I fix this so they only come on when I am in reverse???? 2000 chevy blaze 4.3 L Vortec V6.

Answer: You probably have something faulty or shorted inside the neutral safety switch. Also called the 'park/neutral switch', it is located on the side of the transmission. A quick look underneath and you could see if there is any obvious problem like wiring rubbed through or shorted.

If not, I'd replace the switch. The connectors are glued in from the factory, so if you've never had them or the switch replaced before, I'd recommend getting new pigtail connectors along with the switch and wire them in per the directions.