2015 Tacoma won't start

My daughters 2015 Tacoma, has a starting issue where the signal for the coil of ST Relay only has 9.5vdc when the key is in start. Not enough voltage to pull in relay. I think the problem may be the neutral safety switch, on tranny. Finding schematic drawings for newer vehicles today seems to be very difficult. I am an Electronic engineering Tech, but without drawings, is difficult to troubleshoot. Does anyone have any links to the start schematic? Thanks.

 

Welcome To TW...

 

@caribe makaira

And @JWAYNETACOMA , you've of course verified the battery is healthy, even under load?

 

Welcome to TW!

 

@Dm93 This fella may have the schematic..he seesm to have all kinds of stuff and is quite knowledgeable.

 

Put a known good battery in it. I'm going to bet it starts.

 

Here you go, srry I've been busy all day.
Also have some starting system diagnostics here.
https://www.tacomaworld.com/threads/2nd-gen-information-diagnostics.784008/#post-28042155

 

Thank you. That helps a lot.

 

Check battery cable clamps for corrosion

 

I had an intermittant no-start on an old tired car one time and it turned out to be the positive battery cable: where it connected to the battery clamp most of the indvidual copper strands had corroded away and left only a handful still holding on. I discovered it when I leaned on the cable with my hand a little way back from the battery and it let go at the clamp. The cable still had it's vinyl cover and it looked fine from above: no hint that it was barely hanging on. Reduced cranking voltage to a minimum (or zero) in one direction and charge from the alternator in the other.

 

Good idea, Thanks.

 

Seven years on the truck is a little early for such a problem, but who knows. I'd check the grounds too.

 

Agree 100%. This truck has been a gem for my daughter point a to b. Programming engineers on ECM's have got away with murder, as to why simple electronic sensors will put you on the side of an abandoned road. Old school was O2, fire, fuel. Car went down road just fine. With only 120Kmiles, this truck or any that your paying $40,000 for should not have codes pop. You can tell I'm old school. KISS. "Keep it simple stupid".

 

So is it running now? We like to hear solutions, not just questions.