Thread: '99 Grand Prix GT has code 1810, yet runs great as always, so why the code?

Originally Posted by McFly1999

Can you tell me which connector it is? There are two connectors next to the shift mechanism under the brake booster, and there is a round connector under the throttlebody at the highest point on the transmission. The two connectors next to the shift mechanism seem to small to have 20 pins, and the round one I can't seem to get it unplugged. I disconnected the ECU and reconnected it for now, in case that may help.

Let me know please, and thank you in advance for the help.

It will be the round connector located directly on top of the transmission which is probably about 1-1/4" in diameter. To release the connector, squeeze on the sides of the connector and then pull back while the connector is squeezed. As far as a scanner, a typical scanner will probably not be able to read this data of the switches. So, if you do get one, be sure it will be able to. Some of the guys in here use a tuner to modify the internal data of the tranny which of course shows you the tranny data. I'm sure it would be cheaper than a high end scanner. They could comment on this.

If the price of a scanner or software is too expensive, you'll need to use a voltmeteter/ohmeter to do your checking. I would keep the connector plugged up on the tranny with the engine running and just backstab through the pins so that you can analyze the switch combinations under actual conditions as you move the gear selector through each position. Otherwise, you'll throw more codes if you unplug the connector and there won't be any voltages at all going into the tranny. Or a better alternative would be to backstab the pins at the PCM which would check the entire wiring and you may find it a little easier to get access to the pins. Once you confirm that the switch or wiring is bad, you can unplug the connector (at transmission or PCM) and then use your ohmeter. I would have the engine turned off when you unplug the connector to do your checking. If you need a diagram or better yet a service manual of your vehicle, you can get one at www.alldatadiy.com In the manual, you'll see the pinouts of the connector, the truth table for the switches and all other pertinent information for your diagnosis.

Terry