Engine will not crank and headlights will not come on?

Tiny
CBM804
  • MEMBER
  • 2001 CHEVROLET TAHOE
  • 5.3L
  • V8
  • 2WD
  • AUTOMATIC
  • 253,000 MILES
Changed transmission drove a few miles worked great. Parked car the next day it wouldn't start, it'll crank and try to start but will not run. Check fuel pressure it was low, installed a new fuel pump, same thing good pressure still won't run. Put it on a machine it said crankshaft sensor put a new one still won't start. Checked fire to coils they are firing can keep it running with starting fluid. Put another machine on it it said MAF or vap sensor and something about low voltage. And for some reason the headlights won't come on, all this started at once.
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Tuesday, November 8th, 2022 AT 11:00 AM

9 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

If it runs on starting fluid, then it isn't getting fuel. You mentioned it has good fuel pressure, it's most likely not getting power to the fuel injectors or injector pulse from the PCM.

At each injector, there will be a pink wire. I need you to check for power to those wires. If there is no power, check both injector fuses in the under-hood fuse box.

If you find they do have power, I need you to disconnect one of the injectors. The connector will have two wires, one pink and one another that is different based on the cylinder.

Take a test light and place one end to the positive side of the battery and the opposite side to the wire (not pink) in the injector connector and have someone crank the engine. The test light should pulse on and off.

Let me know what you find.

Take care,

Joe

See pics below.
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Tuesday, November 8th, 2022 AT 8:13 PM
Tiny
CBM804
  • MEMBER
Okay, so, with just the key on I'm showing 5.4 volts when it turns over it jumps around from 5.4 5.1 don't down to 4.8 and 3.5and back through the same sequence. That's touching the none pink wire to the battery.
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Wednesday, November 9th, 2022 AT 4:09 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

The good news is that it appears the PCM is doing its job. The bad news is there isn't enough power to the injectors. They should receive battery voltage (12v)

If you move the pink wiring harness around when checking voltage, does it change?

Let me know.

Joe
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Wednesday, November 9th, 2022 AT 5:06 PM
Tiny
CBM804
  • MEMBER
Yes, it does when I wiggle the harness back towards the front of car close to the plug at the end of the harness.
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Wednesday, November 9th, 2022 AT 5:50 PM
Tiny
CBM804
  • MEMBER
It goes up to 7.7 I got 8.1 one time.
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Wednesday, November 9th, 2022 AT 5:51 PM
Tiny
CBM804
  • MEMBER
Oh, I don't know if it could be my problem but my security light is on also.
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Wednesday, November 9th, 2022 AT 6:25 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
It sounds like you have two different issues going on. Do me a favor. Turn the key to the run position and allow it to stay there for approximately 10 minutes. The security light should turn off. At that point, see if it starts.

And yes, if the security light is staying on, that is likely preventing it from starting.

Let me know.

Joe
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Wednesday, November 9th, 2022 AT 7:28 PM
Tiny
CBM804
  • MEMBER
The light didn't go off and it wouldn't start.
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Thursday, November 10th, 2022 AT 6:52 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
If the light did not turn off, we need to scan the can-bus to determine the cause. I suspect if you have a different key, you tried it, correct? The more I think about it, if that light never turned off, the key isn't the issue. We have something different happening.

As far as a can-scan, it is done in the same way that other scans are done. The difference is1 the scan tool that is used.

CAN stands for controller area network. Basically, there are several modules tied together via a few wires. This will retrieve codes regardless of the module storing the code. In this case, I suspect you will find a B code. If you can retrieve the codes, I will know which direction to go with testing. Otherwise, it becomes a guessing game.

Here is a link that explains how to perform the scan:

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Let me know if this is something you can have done or get a scanner to do it with.

Take care,

Joe
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Thursday, November 10th, 2022 AT 7:12 PM

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