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

[Firebirdracer82]

About the car:

2004 Yukon - 185K miles. It had been sitting a long, long time. I thought that I could cure it with some common fixes, but, alas, I cannot.

Symptoms:

Crank, no start was the initial issue.

If you get in the truck, put the key in, and turn it to "on", before cranking, then the electronics don't work (mirrors, windows, locks, radio, climate control). The headlights don't work, except for the rear lights and one marker light in the front - no headlights either.

It will crank, but won't fire.

But, if you turn the key to off after you crank it, with the door closed, the electronics work (locks, mirrors, windows, radio, headlights - etc.). I believe this is the RAP system.

Cluster is broken and not working at all. I only have the check engine light on the cluster.

THINGS I HAVE DONE DO FAR:

1.) Cleaned the grounds and charged the battery. Verified no spark on crank.
2.) Cleaned PCM connections.
3.) Ordered a new BCM programed to the vin. Installed. Did key relearn - it is recognized since I am getting chime now when the key is left inside the car.
4.) Checked fuses, but perhaps I should check them again.


What do I do next? Help? I am trying to get a working cluster as well to assist in this situation. I do not have a bi-directional scanner - just a simple code reader.

 

[Firebirdracer82]

Also, I forgot to mention, I did change the ignition switch tonight. No change in symptoms.

 

[Fless]

Which grounds were cleaned?

Have you tried adding a ground cable connection between the battery negative and the body?

Done a voltage drop test to both the engine and the body?

 

[Firebirdracer82]

I haven't tried the additional ground thing yet, but I will tomorrow. Since I am getting power to all these units when then key is off (before I open the door) I was focusing more on things inside the cabin. But I might be a wire that's gone bad somewhere along the way.

 

[Firebirdracer82]

And I cleaned the battery leads, the grounds under the driver's door, took the dash off and cleaned the two on either side of it. Checked the ground on the back passenger side of the engine and it is secured. Main ground looked clear at the block, but I did not remove that one there. Cleaned the one in front of the radiator on the drivers side. All done with wire brush in a drill, electric contact cleaner, and then the electric grease.

The story I got on it was it was running but had a parasitic drain, they were going to fix something unrelated, and they had to jump the truck and after that it did not start again. It cranks, but it doesn't start. There are no gauges and and nothing works except for one running light when in the "on" position. When turned off, the RAP allows the radio and everything else to work fine. Very strange.

 

[strutaeng]

Probably multiple issues going on...

1. The clusters on the 03-06 are known to have the lead-free solder originally used on them breakdown and causes parasitic drains. Get it rebuilt by one of the online vendors.

2. They jumped and then it would crank? Or it cranked and didn't fire? That's probably another problem if it cranks but doesn't fire? Does it crank if you jump the starter relay?

3. How long has it sat? It's not uncommon for rats or mice to make nests and chew through the wires. Takes some advanced diagnostic knowledge often (and wire inspection) to find the culprit. Can be a can of worms if that's the case.

 

[Doubeleive]

load test battery if it fails, replace
ohm test power and grounds (any should read basically .00), if you get a funky reading replace it.
if need be connect temporary power & ground wires with known good wires for start test.

 

[Firebirdracer82]

I will start getting going on it today when the rain stops (if it does).

I guess what I would be trying to do is see a couple of things to narrow down my search. I can load test the battery, but I don't suspect it will be the concern.

The fact that everything works in the RAP system when the key is off, but does not work when the key is in on, and the fact it cranks, makes me want to try to figure what circuit this would be on to narrow down where I am chasing the wires. I think the BCM controls the RAP, and the BCM is new and vin matched and doing the same thing as the old BCM.

Where would I narrow my search, or possible easy ways to look? I pulled apart the under hood fuse box and PCM cables and all looked good.

 

[2016Dom]

Just guessing, could it be an OEM anti theft measure

 

[Doubeleive]

I will start getting going on it today when the rain stops (if it does).

I guess what I would be trying to do is see a couple of things to narrow down my search. I can load test the battery, but I don't suspect it will be the concern.

The fact that everything works in the RAP system when the key is off, but does not work when the key is in on, and the fact it cranks, makes me want to try to figure what circuit this would be on to narrow down where I am chasing the wires. I think the BCM controls the RAP, and the BCM is new and vin matched and doing the same thing as the old BCM.

Where would I narrow my search, or possible easy ways to look? I pulled apart the under hood fuse box and PCM cables and all looked good.

@Firebirdracer82 your symptoms are indicative of poor power / ground. When the key is turned to start pretty much all of the power is used by the starter, if the voltage is 10.5 volts or lower that is what gm considers "dead". It also why when you are engaging the starter everything dims, in a low power ground situation things either go out completely or are in such a low voltage state that operation may be erratic or not working at all.
based on your reported problems I would start at the battery and work your way back.
the best way to do that is load test the battery and ohm test the main cables
the cluster does not need to be working or even connected at all to start or drive the vehicle, that has nothing to do with it other than it could be slowly draining power while idle (parasitic drain)
I don't think your problem is the BCM at all.
if the power/grounds all check out (FIRST) then CHECK EVERY FUSE (WITH A METER), THEN down the rabbit hole
I would then maybe be looking at ignition to pcm signal, chaffed or chewed wires, broken wires, water intrusion, fuse box, etc
The bottom line here is it is a process of elimination, it is always best to start at the battery and power/ground, then fuses there have been a lot of time's where a single bad fuse has caused a no start, followed by broken/chaffed wires. Inspect everything carefully.
In any case please report back and let us know if you find the problem as it may help someone else down the road
if you get stuck there are people that can be tagged with further diagnostic info

 

[Firebirdracer82]

Update - played with it a bit more. The stereo and climate control and headlights were a fuse that wasn't doing well.

I am now down to a crank, no start, no gauges.

 

[Firebirdracer82]

I went through and tested each fuse with a test light and apparently seated one of them incorrectly when I inspected them originally.

I went ahead and did the small ground on the back of the engine block for piece of mind - it was corroded a bit so I cut the wire a bit up and put on another ring terminal. No effect yet.

I am trying to source a set of gauges, as I am assuming that problem is internal. And, without gauges, I don't know if the security system is engaged or not.

It will now crank, but not start and all accessories work correctly.

Fuel pressure tested and is within spec.

There is no spark, per a tester. I don't have a tester for the fuel injectors sadly.

 

[Fless]

It's likely not the Passlock system. When that's in play, the engine should start (with ignition, fuel, etc.) but will stall shortly after firing.

You should be able to "rent" a noid light test kit from an autoparts store to determine if the injectors are being commanded (are the plugs wet with gas?), but the no-spark is another issue and should be remedied first.

 

[Firebirdracer82]

Another update:

I purchased a used gauge cluster - there is a CEL light on the used cluster as there was on my broken cluster. I used my extremely simple code reader to try and clear the codes, but the CEL remains. On the plus side, everything seems to work in terms of the interior of the car now.

But, still crank, no start.

There also appears to be a power draw that is continuing, somewhere. I will try to investigate that tomorrow.

I had a thought that, perhaps, the PCM went bad. But, as it's cranking and all the interior systems work, that that is unlikely.

I verified that my coil harness has good ground with a multimeter testing for continuity in the circuit. I also was able to get a pulse at a coil wire while cranking - but only on one prong. One prong was grounded, one pulsed, but no power to two of them with either the key on, or while cranking.

 

[Fless]

What do you suppose is the code for the CEL? Please share.

 

[Fless]

Coil connector pinout for the 5.3 (not sure what engine you have):

Ignition Coil: Diagrams — 2004 GMC Yukon/Denali 2WD V8-5.3L VIN T Service Manual | Operation CHARM

Detailed repair manual for the 2004 GMC Yukon/Denali 2WD V8-5.3L VIN T.

charm.li

Electrical diagrams here (note the "previous" and "next" links at the bottom of the page); 5 & 6:

Engine Controls Diagram 5 — 2004 GMC Yukon/Denali 2WD V8-5.3L VIN T Service Manual | Operation CHARM

Detailed repair manual for the 2004 GMC Yukon/Denali 2WD V8-5.3L VIN T.

charm.li

 

[Firebirdracer82]

Honestly, I have no idea what the CEL is. I tried using my code reader to clear it (as it did on my last Tahoe) but it did not clear the light. I think my code reader (small as it is and such) is connected to the PCM for codes, but, maybe, the two are not connected? But, I think it is connected based on the small signal I do get.

 

[Firebirdracer82]

Update after testing a bit:

I have good ground on the wires to the coils.

I have power to the pink wire (constant power) to the coils.

I do not think I have signal to the C or B connections as indicated in the schematic.

Perhaps this would be more likely a PCM issue or possible Crank or Cam sensors?

 

[Fless]

Maybe need a better scanner to ID that code. It could be critical.

It should run without any cam sensor signal, although the crank could intermittently be long.

But does your scanner show live data, and does it (or the cluster; I can't remember if it does) show rpms while cranking?

Pin B should be a low (ground) reference provided by the PCM. Test for that ground, or substitute a temporary ground?

 

[Doubeleive]

1. Check INJ 1 and INJ 2 Fuses (Underhood).
2. Swap IGN Relay (Underhood).
3. Confirm Tachometer movement during cranking.
4. Inspect CKP Sensor wiring above the starter.
5. Verify 12V on the Pink wire at any coil.
6. RE-CHECK THE GROUND FOR THE HEAD/S