No Crank / No Start (Most times)

2006 V6 4.0L Auto with 290K kms (180K miles) started having a no crank no start issue a few weeks ago. Trouble shooting actions and results:

• Battery tested fine (passed load test)
• Won't start in either P or N
• Starter relay ok (tried another working relay same results so assume it's good)
• Starter relay doesn't seem to be getting a signal to engage
• Will start every time by putting 12 volts to the starter relay port (I assume that indicates all good from the relay to the starter and the starter is good)
• Will also start properly (ie with the key) after driving it around the block a few times for, in some cases, over 5 hrs after, but not the next day for example
• Had a P0705 error code (hasn't come back yet after clearing and driving it around for a couple kms), but believe it will eventually come back
• Checked the connector block as per the Tech Service Bulletin - T-SB-0277-09 - no corrosion or any obvious connection issues. http://www.scribd.com/doc/18857706/TSB027709
• Checked the connector to the NSS, seems ok (clean, no corrosion)
• Seems to take 3 to 4 sec to engage drive when shifting from park and it's a harsh shift 80% of the time

Leaning towards a faulty NSS, but not sure why it will start after driving it around. Not sure an easy way to troubleshoot or bypass the NSS.

Any thoughts on what else to look at, test or replace? Thinking of giving up and bringing it to my mechanic, but based on my discussions with him, he doesn't seem to have any ideas (at least without looking at it himself).

I've had the truck for 7 months now, so not a lot of history known. I'm also fairly new to working on vehicles (other than oil changes and tire rotations) so feel free to dumb down your suggestions accordingly.

Thanks.

 

I don't have time to help in detail at the moment but you can start here.

https://www.tacomaworld.com/threads/2nd-gen-information-diagnostics.784008/#post-28042155

 

Thanks for the info @Dm93. I was pretty sure it was the neutral safety switch, but really didn't have the knowledge or tools to troubleshoot it so brought it to my mechanic. Their troubleshooting showed some anomalies with voltage readings from the NSS while switching gears so it was replaced and it seemed to resolve the problem. Probably something I could have attempted myself, but I'm glad I didn't as it took them quite some time to get the old switch off due to corrosion. They had it up on a hoist and it was tough, so would have been a pretty miserable job trying to do it laying under the truck. I guess I can chalk this up to a bad NSS.

 

An electrical component going bad is tricky. You get a multi meter anywhere close to it, it'll test good. Put your tools away, wash your hands, go back, it'll fail.