Where is the transmission range sensor/neutral safety switch on a Daewoo Lanos?

I am having problems with my 2002 Daewoo Lanos not cranking or starting randomly. In the past, I have been able to resolve this problem by inserting the key into the interlock slot on the transmission shifter, cycling through all the gears, and back to P or N. However, even that no longer works all the time.

I needed to go to a doctor’s appointment this morning, while it was still somewhat cold, and I could not get the car to start. I ended up driving my truck instead. When I got back, I tried to start the Daewoo, and the same thing happened, but after fiddling with the transmission shifter, it eventually started.

Still, I don’t want to have a car which will not start reliably. Especially because this problem could occur far from home, in a terrible neighborhood, etc.

I am trying to figure out where is the switch or sensor which controls this function. If it is located inside the transmisison itself, then I need to figure out if it is accessible without taking off anything more complicated than the fluid pan.

It’s located on the transmission below where the shift cable attaches to the shaft lever.

Tester

So I ended up ordering the part online from RockAuto. GM p/n 12450161, identical to the one which was on the car. I disconnected the battery, swapped out the transmission range sensor, reconnected the battery, and tried to start it, and it does the same thing–no crank, no start. Any ideas? I’d like to repair this car, if possible, as I don’t really wish to buy another vehicle right now.

Check fuse #2, 30 amp in the fuse box under the hood to see if it’s blown.

If not. then I would try smacking the starter with something like hammer to see if it’ll start.

Tester

Did you confirm the shift cable is not broken?? (ask me why I ask… lol)

Pull a wiring diagram, start at the furthest point (starter) and check for a signal when trying to start it work your way up the line until you find the issue check the simple stuff 1st as Tester mentioned… If by yourself, get a generic 2 wire back up alarm and use it in place of a test light, if it beeps, you got power, no beep, no power…

1 Like

It may very well be a problem with the shift cable, as when it first started acting up, I got it to start by cycling through the gears, and my wife got it to start by smacking the transmission shifter. However, for more than a week, it wouldn’t start no matter what, and yesterday I replaced the transmission range sensor (which made no difference).

Did you move the shifter from park to the lowest gear (1st?) and back while holding the key to the start position?? and hold the key to start while moving the shifter back and forth…

IF it is cable ish related, the new NSW could be out of adjustment or the cable stretched or broken…

The starter won’t crank the engine unless its inputs are to spec.

Well, I worked on it some more today. I had my wife get in the driver’s seat and try to start it while I wiggled the wiring harness at the transmission range sensor, etc. Since I heard the fuel injectors firing on each unsuccessful starting attempt, I removed the fuel pump relay to avoid dumping fuel into the engine.

I have the factory service manual, so I referred to the troubleshooting steps which they give under “no crank”. However, once I got to step 31 under Engine Electrical 1E-7, I could not find where exactly connector C104 is on the vehicle. I surmised that it is one of the connectors on the PCM, however nowhere are those connectors labeled. The PCM is located under the front passenger seat, and they suggest removing the seat to access it.

I found that the neutral safety switch (pins G and E on the transmission range sensor) were closed as expected, and the old and new range sensor both tested ok. I did not have the control voltage to the starter to engage the relay.

Since I could not figure out the location of several of the connectors which the FSM said to check, I started taking off interior panels to check for loose or damaged wiring. I pulled off the plastic casing around the steering column, the knee bolster, the center console, but wiggling the connectors and wires made not difference trying to start.

Eventually, I moved the front passenger seat all the way forward, reached under the plastic splash shield on top of the PCM, and pushed on the blue connector. Then I was able to crank the engine. I surmise that there is either something wrong with this connector or a cracked solder joint in the PCM. Any ideas on what to do next?

1 Like

Unplug it and check to make sure a wire/terminal has not come loose in the connector, and or push/pull on the wires one at a time until it starts… look at the pins in the PCM for any loos pins, gently see if any will move…
You might need to remove the seat for this, should be pretty easy to do so…

There might be oxidized contacts on the connector too. I had this issue on a 2003 Silhouette. A sensor was not working. I unplugged the reconnected the sensor maybe three times. After that the sensor worked again. Since it’s a free fix if it works, it’s worth a try.