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I’ve been having trouble with my 02 Tacoma. I got a CEL and went to get it checked. P1780 Parking Neutral Switch. I have been having weird problems like when I turn my dash lights on the brake lights turn on full brightness including my 3rd brake light and my front parking lights. When I press on break during the day my dashboard lights turn on and my radio dims. Recently the brake light on my dashboard has been on as well even though I do not have it engaged. When I turn on my truck and stay in idle the truck switches gears going as high as about 1500 RPM, when I am braking at a traffic light I feel like the truck wants to move foward a little. Not sure what it is, I appreciate any help or suggestions.
 

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Mambeau / Admin
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What are the details on the truck? 5-lug or 6-lug? Which engine?

Edit to Add:

Does this Taco have cruise control?
 

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Mambeau / Admin
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Also take a look at this 2010 thread, which involved a P1780 code on a 2002 Taco:

 

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Mambeau / Admin
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Let's start with the lights. Your taillights and dash illumination lights are on the same circuit. The brake lights are on a separate circuit.

My first guess is that you've got one or more electrical faults (short circuit; disconnects) in these circuits - most probably in the wiring that runs back to the rear.

Here (attached) are the 2002 taillight / dash illumination and the brake light circuit wiring diagrams.

Both circuits run through the BN7 connector, which is located underneath the driver's seat. Find the BN7 connector and check for good connection, loose wires, crimped wires, etc.

A short or wiring fault inside either of the taillight pods would also explain the cross-weirdness between the dash illumination and the brake lights.

The brake light circuit connects to the Shift Lock Control Relay, so it's possible that transient current weirdness in the brake light circuit could affect the transmission controls.

Or it could simply be a Park / Neutral Position Switch gone bad (see the other thread I recommended).
 

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