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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), GMC Mechanic
Category: GM
Satisfied Customers: 5783
Experience:  GM Grand Master Technician 2007. 14 years experience.
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GM sierra: We have a crank no start situation with a 2005 gmc

Customer Question

We have a crank no start situation with a 2005 gmc sierra duramax 3500 tow truck. The codes we are getting from the computer are P0900 and P0653.
Submitted: 1 year ago.
Category: GM
Customer: replied 1 year ago.
This is a Diesel Duramax 6.6 L
Expert:  GM Tech (Cam) replied 1 year ago.
Hi there, I am CAm. If you clear th codes, what happens?
Customer: replied 1 year ago.
when we clear the codes they come right back. Crank crank continuously and no start
Expert:  GM Tech (Cam) replied 1 year ago.
Ok, that is a 5v reference issue. Do you have a scanner that can view live engine data?
Customer: replied 1 year ago.
yes we have a maxidas ds708
Expert:  GM Tech (Cam) replied 1 year ago.
OK With key on, what is the 5vReference voltage 2 showing with the scan tool?
Customer: replied 1 year ago.
where can we check this on the scan tool in the live data?
Expert:  GM Tech (Cam) replied 1 year ago.
Yes, live data should have that parameter, or atleast it does with the GM tool. I am not sure about aftermarket tools.
Customer: replied 1 year ago.
now when we plug the scan tool again we get u0106, p2128, p0653, p0090. sometimes when we clear it comes back with only p0090 and p0653 we clear again and we get u0106, p2128, p0653, p0090.
Customer: replied 1 year ago.
we see no option for 5vreference in live data
Customer: replied 1 year ago.
battery also dies very quickly
Expert:  GM Tech (Cam) replied 1 year ago.
We're going to need a scanner that will read those. Many of those codes relate to the sensors, and could be nothing more than a bad wiring connection somewhere. However I don't want to simply start replacing things until we know which direction to go.
Customer: replied 1 year ago.
ok let us take a closer look and see if we can get any info in regards ***** ***** reference. Is there a possibility that the ecm itself could be bad ?
Expert:  GM Tech (Cam) replied 1 year ago.
That does tend to support a short in the wiring. Can you start by having a look closely around the valve cover connectors. Yes the ecm could be bad but I don't like just guessing at parts.
Customer: replied 1 year ago.
5v reference 2 fluctuates between 5.3 and 5.4
Customer: replied 1 year ago.
actually i have the numbers for you the 5v reference 2 fluctuates between 5.2, 5.3 and 5.4
Customer: replied 1 year ago.
also not sure if it is important to know that the FRP Regulator fuel flow command is red at 40000. there are 2 wires coming from the fuel pressure regulator that appear to be after market and they are not connected to anything. We don't know where they connect to. Not sure if this is related or not to our issue.
Expert:  GM Tech (Cam) replied 1 year ago.
Sorry for the delay so reading more than 5.2 si bad. Unplug each of the items off the 5volt 2 reference in the schematic in the attached page and see which makes it drop.
Customer: replied 1 year ago.
Where is the boost pressure sensor located ? where is the turbo charger vane position sensor located ?
Expert:  GM Tech (Cam) replied 1 year ago.
Turbo vane sensor is on top of the turbo and the body of the sensor is at the other end of the white cable down on the left valve cover area. Boost sensor is on the aluminum housing, passengers side almost centre. its a 3 wire flat sensor, like the MAP sensors on cars.
Customer: replied 1 year ago.
we disconnected a wire connector right behind the ac compressor , which leads into the big wiring harnesses and that dropped the reference back to 5.0 volts but I don't know where it leads on either ends because its in the harness
Expert:  GM Tech (Cam) replied 1 year ago.
What wire colours? Does it start nw?
Customer: replied 1 year ago.
black, golden yellow, brown with the white stripe and it connects to a harness that looks like grey, turquoise and orange with a black stripe.
Customer: replied 1 year ago.
please see the attached picture of it. no it doesn't start yet.
Expert:  GM Tech (Cam) replied 1 year ago.
Is there a chip in this truck?
Customer: replied 1 year ago.
when trying to start the fuel injector is pushing fuel out of the top of the injector and pushing the fuel return line off. still will not start. acts like it wants to start though. smoke comes out of tail pipe.
Customer: replied 1 year ago.
not sure about the chip
Expert:  GM Tech (Cam) replied 1 year ago.
The grey, green and orange with a black stripe is the boost pressure sensor, but you have it going into another connector and that tells me there is some sort of a power up device in there messing this up
Customer: replied 1 year ago.
what is the power up device you are referring to?
Expert:  GM Tech (Cam) replied 1 year ago.
A chip or programmer to interface with the system and trick the Powertrain Control Module (PCM) into thinking the reading are off so it adds more power.
Customer: replied 1 year ago.
we don't know if there is a chip or not in this tow truck. Any way we can find out? What are our next steps here?
Expert:  GM Tech (Cam) replied 1 year ago.
Follow the wire in the harness back a bit Also show me more pictures taken a little further out.
Customer: replied 1 year ago.
where will the chip be located ?
Expert:  GM Tech (Cam) replied 1 year ago.
Usually they are routed to the fuse block area.
Customer: replied 1 year ago.
is this the chip you are referring to?
Expert:  GM Tech (Cam) replied 1 year ago.
Nope that is the body of the turbo vane position sensor.
Customer: replied 1 year ago.
does this look after market or factory?
Expert:  GM Tech (Cam) replied 1 year ago.
That looks like a mess!!! But no that dos not look factory.
Customer: replied 1 year ago.
so where do you suggest we go from here?
Expert:  GM Tech (Cam) replied 1 year ago.
I would like to see what is in that heat shrink and what has been changed in the wiring to that sensor. It looks like its been extended or something added into it.
Customer: replied 1 year ago.
this is what is underneath the heat shrink
Expert:  GM Tech (Cam) replied 1 year ago.
OK so just a hell of a mess. they are not shorted out to each other then are they? With just the grey/yellow/orange black off, it does not show more than 5V at the reference voltage any more?
Customer: replied 1 year ago.
yep that is correct
Expert:  GM Tech (Cam) replied 1 year ago.
Ok, clear the code and see what comes back with only that disconnected.
Customer: replied 1 year ago.
ok will do so and send you the results
Expert:  GM Tech (Cam) replied 1 year ago.
ok