K1500 Wiring issues

I have a 97 K1500 (350/4L60E) and I am having some issues. The biggest one (and probably the easiest one to fix) is that my left taillight doesn't work. The running light works fine but not the brake or blinker. My Haynes manual is pretty much useless when it comes to wiring diagrams so I was wondering if anyone had a way of troubleshooting the plug that goes into the circuit board in the taillight. The circuit board should be fine since I just replaced it. The other problem is that my check engine light is on and something is wrong with the OBDII port that makes it where a code reader won't read anything through it. I don't know if there is a way to test that but I really don't want to take it to the dealer. Thanks for any help

I have a 97 K1500 (350/4L60E) and I am having some issues. The biggest one (and probably the easiest one to fix) is that my left taillight doesn't work. The running light works fine but not the brake or blinker. My Haynes manual is pretty much useless when it comes to wiring diagrams so I was wondering if anyone had a way of troubleshooting the plug that goes into the circuit board in the taillight. The circuit board should be fine since I just replaced it. The other problem is that my check engine light is on and something is wrong with the OBDII port that makes it where a code reader won't read anything through it. I don't know if there is a way to test that but I really don't want to take it to the dealer. Thanks for any help

Pitch the haynes in trash can and get some good repair info.
Good factory manual or a all data online sub will have all wiring diagrams and repair info.
http://www.alldata.com/products/diy/index.html

On the tail light a good old bulb type test light will check it out for you.
Check for good power and good ground to it.
To check for ground hook test light to positive wire and touch the end to ground.
If a good ground the test light will light up good.

On checking for codes check for power and ground on the OBD11 plug.
A bad fuse will nock out power to it.
Somes parts places like AZ will read out codes for free.
Just get code without buying parts they try to sell you and post back codes and someonme will help you.
Good Luck and let us know how it goes.

That is how I found out that the OBDII port was screwed up. When it threw a code, I took it to Advance to get them to read it. When they hooked up the reader, it said something along the lines of "No Vehicle Detected" or something like that. Where exactly am I supposed to have power and ground on the port?

That is how I found out that the OBDII port was screwed up. When it threw a code, I took it to Advance to get them to read it. When they hooked up the reader, it said something along the lines of "No Vehicle Detected" or something like that. Where exactly am I supposed to have power and ground on the port?

http://www.troublecodes.net/OBD2/

Pin 16 should have 12 volts battery power.
Check all fuses.
Usually bad fuse.

It may not be a power problem at the OBDII port. If they connected a scan tool to the port and the tool powered up, power at the port is good. (unless they have a self powered scan tool, which wouldn't matter if there was power or not) Your problem is probably in the serial data line. Could be shorted either to b+ or b-, or you could have a bad module not communicating, or with an internal fault bringing down the serial data line. The fuse that powers the OBDII plug is the cig lighter fuse just in case you want to check that.

Ok. I just went out and checked the wires to the circuit board with a test light. Using the plug for the passenger side as a guide, I tested the wires on the driver side. Everything was the same for both sides so I guess I just bought another crap part. And H1HUMMERMAN, I think you just solved my problem with my OBDII port. My cig lighter fuse has been blown for a while. I didn't replace it because I was trying to quit smoking. I was hoping it would help if I didn't have a lighter. Now that I have replaced that fuse, I am going to go to Advance again to get a refund on that piece of junk they sold me and get them to plug up their scanner again. Thanks a lot guys. I will post later today and hopefully be able to say that all this is taken care of.

Ok. I just went out and checked the wires to the circuit board with a test light. Using the plug for the passenger side as a guide, I tested the wires on the driver side. Everything was the same for both sides so I guess I just bought another crap part. And H1HUMMERMAN, I think you just solved my problem with my OBDII port. My cig lighter fuse has been blown for a while. I didn't replace it because I was trying to quit smoking. I was hoping it would help if I didn't have a lighter. Now that I have replaced that fuse, I am going to go to Advance again to get a refund on that piece of junk they sold me and get them to plug up their scanner again. Thanks a lot guys. I will post later today and hopefully be able to say that all this is taken care of.

You are welcome and let us know how it goes.
Post back any codes you get.
Good Luck