Truck will not start from ignition

So, when he jumps it from under the hood, I imagine he is removing the relay and jumping power straight to the starter terminal?

If this is the case, then we have a control issue or even a relay issue.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

So, the way this works is the ignition switch feeds power to the relay through the AM2 fuse and then ST3 fuse. Then it goes through the junction connector and back to the relay on the green/yellow wire.

This requires the relay to be closed and the way that happens is the ECM sends power from the STA (starter) terminal in the ECM through the junction connector on the pink wire. Sends it to the TVIP ECU where it sends power through the junction connector on the Green/red wire to the relay on terminal 2.

Then this goes through the relay and energizes the relay and returns to ground through the other green/red wire from terminal 1.

So, we need to remove the relay and check for 12 volts when you are turning the key to start on terminal 3 and 2. Then we need to check for a good ground on terminal 1.

https://www.2carpros.com/articles/how-to-check-wiring

I assume you will have voltage on terminal 3 but not on 2. Which means we need to suspect the ECM or TVIP ECU is the issue. Basically, we need to trace power back through the system.

I would not scrap the truck over this issue until we find out what this is.

I attached the wiring diagram so you can follow this voltage path. Let me know if you have questions on this.

Hi,

First, scrapping the truck shouldn't be a consideration. With the market today, it still has value. One that is likely more than you expect. The tracking system is related to the GPS, so I'm not sure that would be a consideration.

Now, if it won't start with the key, rather than trying to find a tracking device, I would start by testing the starting system itself. We need to determine the location of the power loss.

We know that you can jump (I'm assuming) the starter relay. So, the trigger wire is good going to the starter and there is power at the relay.

I attached the starting circuit schematic below. There are several fuses I need you to check. In addition to checking the fuse, it's important to confirm there is power to and from the fuse.

Straight from the battery, the ST3 and AM2 fuses in the under-hood fuse box receive power. Check them first. Make sure they have power to and from.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

If they do, I need you to check the STA fuse in the fuse box under the dash. Do the same thing. Check for power.

Note that the STA fuse will only have power when the key is in the start position. If it does, then remove the starter relay in the under-hood fuse box.

If you look at the relay, there will be 4 pins. They are numbered. Numbers 85 and 86 are the primary sides. Numbers 87 and 30 are the secondary. Power has to make it to the primary side and to ground for the relay to be triggered. When triggered, power goes from pin 87 through the now-closed circuit and out pin 30 and then to the starter solenoid.

So, if there is another relay with the same part number, switch them. If there isn't, here is a link that explains how to test one.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Remember this. With the relay out and the key on, one pin on the primary side (55 or 56) will have power when the key is switched to start. The opposite will be ground. Confirm one of them does in fact have power.

The same thing is true with the secondary side. Either pin 87 or pin 30 will have power. However, it will be 12v at all times when the key is on. Confirm that as well.

I know this sounds like a lot. Please let me know if you have questions. Also, remember the NSS was bypassed, so power should be sent to the primary side when the key is in the start position regardless of if it is in gear.

Take care,

Joe

See pics below. Pics 3 and 4 show the fuse locations and starter relay.

Hi,

Sounds good. If you can, let me know what is found. I'm interested in knowing what is happening.

Take care,

Joe

Hi,

Chances are that could be done. However, this one wouldn't be simple because of the multiple circuits involved.

See if you have any luck with tracking down where power is lost. If we can determine that, we can fix it.

Take care,

Joe

Sure. I will have to approve his comments each time he posts on this thread because only you and our Experts can post on these without approval.

However, if he just creates an account and then posts on this link, we can work through it with him.

Basically, we will need the actual voltage measurements that he is getting when checking the points that we are saying. Just saying that they are all good is most likely not going to lead us to the fix. I have worked with many mechanics over the years and that normally means that the measurement was not taken but the assumption of "it can't be that" is made which results in the comment of they are all ok.

Please be clear, I am not suggesting that this mechanic is doing that as it is rare that they will tell you what the voltage readings are in reporting to you what he has done but he should have them.

So, if he has them, we will need to start with this part of my first post in order to start to figure out what is going on.

"So, we need to remove the relay and check for 12 volts when you are turning the key to start on terminal 3 and 2. Then we need to check for a good ground on terminal 1."

Simply send him a copy of this web address and have him create a membership, which is free, and then he will be able to post on this with what his findings are.

Thanks