Truck stalled after hitting a bump, will not start?

Hi,

In most cases, a crank with no start is either the result of an ignition issue or fuel. We need to determine which is causing the problem.

Here is what I need you to do. See if the engine starts if you use starting fluid. If it does and then stalls, we will know it's fuel-related. If there is no change, then I need you to check for spark at the spark plugs.

Here is a link that explains how to check:

https://www.2carpros.com/articles/how-to-check-for-ignition-spark

As far as a fuel pump relay, pay attention to see if you can hear the pump prime for a second when the key is first turned to the on position. There is also an automatic shutdown relay (ASD) relay that may be an issue. Either way, both will prevent the pump from running.

Try this and let me know what you find.

Take care,

Joe

Hi,

If the ASD checks good, we need to check a couple of fuses and the pump relay.

If you look below, I attached a pic from the schematic. Check fuses 70 and 78 in the underhood fuse box. If they are good, remove the relay and locate connector pins 85 and 30 for the relay. Connector 85 should have power when the run start relay is closed. Check if that is the case.

Pin 30 should have B+ at all times. Confirm that as well. If they both get power, then I need you to jump connector pins 30 and 87 of the fuel pump relay to see if the pump turns on. If it does, then we likely lost ground at connector 86 which is provided via the PCM. If it doesn't turn on, we need to check if there is power at the pump when these are jumped.

Here is a link you may find helpful when testing the relay and its circuit:

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

Let me know what you find or if you have other questions.

Take care,

Joe

See pic below.

Hi,

The only way is to check for power and ground at the wiring. Is that something you are comfortable performing? Let me know.

Joe

You know what, let's try this in a different way that will be easier. Fuse 70 shouldn't have any power when the key is off. When you first turn the key on, it should have power. Check that. Do this with a helper so you can tell if power is available as soon as the key is turned on.

If it is, then I need you to locate the C3 connector at the power distribution center, locate pin 25 (brown wire), and check for continuity to ground when the key is turned on. A ground path should be provided to actuate the primary side of the relay and engage the secondary.

Let me know what you find.

Joe

See pics below.

Hi,

Fuse 70 is what sends power to the fuel pump once the relay is completed. So, either we have a faulty printed circuit board, the PCM isn't providing a ground path, or there is an open in the PCM not letting power reach the pump relay.

I don't want to say it, but I suspect the PCB is faulty. The bump may have caused a solder joint to crack.

Let me know if you are comfortable checking pin 25 on the C3 connector for continuity to ground. If you have a test lamp, connect the alligator clip side to the battery positive. The tester side goes to pin 25 on the PCM side. Have a helper turn the key to the run and then start positions to see if the test light turns on.

Let me know.

Joe

Hi,

That would indicate the PCM isn't providing a ground path. On the other hand, you also indicated there is no power to fuse 70 when the key is turned on. Based on that, we have two different problems. Are you certain there is no power to fuse 70? And on the PCM itself, pin 25 doesn't provide a ground path?

I want to say the PCB/TIPM is faulty based on no power. The ground is something different. I wouldn't think both would fail at the same time.

Let me know.

Joe

Hi,

Anything is possible. I think checking the connector pin is a good idea. When you do it, make sure there are no cracks or damage on the pin. It is a somewhat common issue.

Let me know what you find.

Joe