P1780 code for 2001 Echo

[thecommodore]

Hi,

The check engine light for my Echo is lit, and my friend who scanned it got the "P1780" code, which refers to the park/neutral safety switch. He recently replaced the starter, and in the course of doing so, he had to disconnect the battery a couple of times. He also replaced the rear tail light assemblies (I bought them, but didn't know how to put them in). After all this work was done, the check engine light came on, and the left rear tail lights started acting funky - the left rear turn signal doesn't work when the brake is on, but works fine when the brake is off. Also, the left brake light doesn't work in reverse, but works fine in park or the forward gears.

With all that said, I saw this thread discussing a similar problem:

Ck Eng Light P1780

In that thread, a poster said that most of the time, this problem is due to a pinched or broken wire going from the neutral safety switch to the rear tail lights/back up lights. That thread related to a Camry. Could the same thing be happening with my car?

Thanks so much in advance for your help.

[thecommodore]

To update:

My friend who worked on my car looked at the new tail light that was malfunctioning and found that one of the plugs for the new lights was bent. He fixed that and now the lights work fine.

Also, there was never a problem with the park/neutral safety switch as I was never able to start the car in any gear.

I've read that if you disconnect the battery, it erases everything that was on the car's computer, and if the "check engine" light doesn't come back on after three "warm up cycles" I should be okay and able to pass a California smog test. Is this true?