The strangest problem I have ever encountered on a project - Crank, no start, no gauges, weird issues. Help!

[Doubeleive]

there are some wires on the pcm harness to check, I just do not know which ones in particular, rockola should know, not sure when he will respond back
in the mean time you could google or check charm.li, you will want to use correct parameters the 8th digit in your vin denotes the engine type
for instance vin T is pretty common but is not all of the available types

Fuel System — 2005 Chevrolet Tahoe 2WD V8-5.3L VIN T Service Manual | Operation CHARM

Detailed repair manual for the 2005 Chevrolet Tahoe 2WD V8-5.3L VIN T.

charm.li

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[Doubeleive]

Fuel Cutoff Mode
The PCM cuts OFF fuel from the fuel injectors when the following conditions are met in order to protect the powertrain from damage and improve driveability:
The ignition is OFF. This prevents engine run-on.
The ignition is ON but there is no ignition reference signal. This prevents flooding or backfiring.
The engine speed is too high, above red line.
The vehicle speed is too high, above rated tire speed.
During an extended, high speed, closed throttle coast down--This reduces emissions and increases engine braking.
During extended deceleration, in order to prevent damage to the catalytic converters

 

[Doubeleive]

at some point here you're probably going to need to invest in a scan tool, something beyond a obd reader.
The good thing is they pay for themselves over time by not having to take it to a dealer or shop.
If you are computer savvy and even have a older laptop laying around you can get away with a vcx nano and tech2win and make that work but it can be a bear to get the software working. the vcx runs about $120 last time I checked

 

[Firebirdracer82]

at some point here you're probably going to need to invest in a scan tool, something beyond a obd reader.
The good thing is they pay for themselves over time by not having to take it to a dealer or shop.
If you are computer savvy and even have a older laptop laying around you can get away with a vcx nano and tech2win and make that work but it can be a bear to get the software working. the vcx runs about $120 last time I checked

I'd agree with you 100% on the scan tool. I'll keep an eye out for a used on, since I work on cars a decent amount myself.

I am starting to suspect that it's the crank position sensor more than the PCM as some of the PCM functions seem to be alive (fuel gauge, etc.). It wouldn't preclude that it would be a failure on some wire or circuit, but at least some of the functions appear to be functional.

The story I got on the vehicle was that it ran to where it was, but there was a battery drain and that they jumped the vehicle but it would crank but not fire with the jump. It then sat for an extended period of time. My last one, it was a crank sensor that was an issue. It could be that this is the same situation. It's not a hard job to replace, but I don't want to throw parts and want to narrow down if it's the crank position sensor or the PCM itself and with partial function of the PCM I am leaning more towards crank sensor.


Another thing I should report on this is that I don't have the gear selector on the dash even with the replacement cluster which might point to something with the neutral safety switch.

 

[Jimmyy]

This guy start with a scanner but shows how to check with a meter. This is for the power side of the sensor.

 

[Doubeleive]

I'd agree with you 100% on the scan tool. I'll keep an eye out for a used on, since I work on cars a decent amount myself.

I am starting to suspect that it's the crank position sensor more than the PCM as some of the PCM functions seem to be alive (fuel gauge, etc.). It wouldn't preclude that it would be a failure on some wire or circuit, but at least some of the functions appear to be functional.

The story I got on the vehicle was that it ran to where it was, but there was a battery drain and that they jumped the vehicle but it would crank but not fire with the jump. It then sat for an extended period of time. My last one, it was a crank sensor that was an issue. It could be that this is the same situation. It's not a hard job to replace, but I don't want to throw parts and want to narrow down if it's the crank position sensor or the PCM itself and with partial function of the PCM I am leaning more towards crank sensor.


Another thing I should report on this is that I don't have the gear selector on the dash even with the replacement cluster which might point to something with the neutral safety switch.

if it was the safety switch there would be no crank

 

[Firebirdracer82]

This guy start with a scanner but shows how to check with a meter. This is for the power side of the sensor.

Thank you, that might be a very helpful video! I will start testing again when the rain stops hopefully.

 

[Firebirdracer82]

This guy start with a scanner but shows how to check with a meter. This is for the power side of the sensor.

I performed the test (first one) in this video. I am getting 8.75 volts at the terminals so I should have signal from the PCM, even while it's low. It might be that there is a pre-existing drain on this vehicle. I think I am going to bite the bullet and order the crank sensor for tomorrow and see if that's it.

 

[LsHart]

Update for the morning:

Cleaned grounds on left side of engine block, for peace of mind. - no change.

Used test light on a fuel injector - I cannot figure out how to get it to sit to see if there is a pulse, but one wire has power at least, may use multimeter to go back a verify ground on the other prong.

Verified that my throttle body was going with my gas pedal. Since its the electric throttle body I was assuming that it would run through the PCM, and that maybe if I verified that was working I could figure it wasn't the PCM, but I don't know.

Noid light kit as I stated before.

 

[Firebirdracer82]

Update for the morning:

I replaced the crank sensor with a new Delphi and no change.

I think it's gotta be the PCM at this point for whatever reason. I'll do a little more testing on it but that's likely.

I also know I have a blown oil pressure sensor and I am not sure if that would be an issue with starting.

Getting sad about this one but will persist.

 

[Doubeleive]

Update for the morning:

I replaced the crank sensor with a new Delphi and no change.

I think it's gotta be the PCM at this point for whatever reason. I'll do a little more testing on it but that's likely.

I also know I have a blown oil pressure sensor and I am not sure if that would be an issue with starting.

Getting sad about this one but will persist.

also should not be related to oil pressure because that is a known part that fails eventually and it fails fantastically giving 00-1000+ readings and it does not affect anything..
again a diagnostic tool is going to probably be your best bet so you can look at the data being given to the pcm
did you check the coil pack harness for broken ground? that's one that can cause a no start

 

[Firebirdracer82]

also should not be related to oil pressure because that is a known part that fails eventually and it fails fantastically giving 00-1000+ readings and it does not affect anything..
again a diagnostic tool is going to probably be your best bet so you can look at the data being given to the pcm
did you check the coil pack harness for broken ground? that's one that can cause a no start

Yes, all grounds checked and cleaned at this point. Verified continuity to ground as well. I think I can get the computer flashed for $150 or so, but that's kinda the end of the budget on this car for some time. I wish I had a buddy that had a good scan tool for me to borrow. They're just so pricey.

 

[Doubeleive]

Yes, all grounds checked and cleaned at this point. Verified continuity to ground as well. I think I can get the computer flashed for $150 or so, but that's kinda the end of the budget on this car for some time. I wish I had a buddy that had a good scan tool for me to borrow. They're just so pricey.

I take it your just trying to flip this thing?

 

[Firebirdracer82]

I take it your just trying to flip this thing?

Nah was/am planning on keeping it. Really love these Tahoes/suburbans. I had a Tahoe before that I really liked but traded it to an Excursion. I found this one and figured I could fix it again and get rid of the V10 since the idea of a plug shooting out of the engine scared me too much.

 

[Doubeleive]

Nah was/am planning on keeping it. Really love these Tahoes/suburbans. I had a Tahoe before that I really liked but traded it to an Excursion. I found this one and figured I could fix it again and get rid of the V10 since the idea of a plug shooting out of the engine scared me too much.

lol, I have had a plug shoot out of the engine before, not a ferd but none the less a WTF moment haha.
without a scanner all you have is visual so I would be using a flashlight and inspecting all of the harness by both light and feels wherever anything sits or rest's on another thing or on the frame, maybe look for any corrosion on the pcm connector.
instead of shooting the $150 in the dark maybe try and get a mobile tech to come by.

 

[Doubeleive]

or order a vcx nano and try to find a old laptop at a thrift store or yard sale, facebook marketplace, craigslist, offer up.

 

[Firebirdracer82]

I just want to get this going - and verify that the transmission and everything works - before getting rid of the Excursion.

 

[Firebirdracer82]

Opened the PCM and think I found evidence of a short, but I am not the best at electrical.

 

[Joseph Garcia]

I just want to get this going - and verify that the transmission and everything works - before getting rid of the Excursion.

I really feel for your frustration regarding this issue. It really s**ks to chase an issue and not be able to get it resolved.

That being said, you've received a number of suggestions that involve the purchase/borrow and use of a quality bi-directional scanner to further diagnose your issue and work toward a solution. I believe that your choice now is to acquire a scanner or continue to fire the parts cannon at your issue, hoping that you get lucky.

 

[Firebirdracer82]

I really feel for your frustration regarding this issue. It really s**ks to chase an issue and not be able to get it resolved.

That being said, you've received a number of suggestions that involve the purchase/borrow and use of a quality bi-directional scanner to further diagnose your issue and work toward a solution. I believe that your choice now is to acquire a scanner or continue to fire the parts cannon at your issue, hoping that you get lucky.

Agree wholeheartedly. And I thank everyone for the help here. I might start calling some guys I know to see if any friends of friends have a scanner that's ideal. I wish that the auto parts store rented them. I've been trying to go around Facebook marketplace to see if I can find one in the budget, and for further projects in the future.