Need advise asap U1000 code

[NWTDIESEL]

Im on the road and truck ran fine all the way to New Mexico, after i got here and shut the truck off i have had nothing bt problems. My truck will start then die, idle rough then smooth, then run fine then die..... I got a U1000 code a couple times. Now it starts up then dies right away. I cant figure it out, dealership is booked till next week. I have access to a shop here tonight but im stumped and dont know what to even lok for anymore. Ive gone over the fuses, ecm wires, harness connections...

What should i look for?

[blksmok]

Found this:

Subject: All GM Vehicles Using Class 2 Communications Diagnostic Strategy for DTC U1000 or U1255 - PIT3154 - (09/10/2004)

Models: (All GM vehicles using Class 2 communications)

The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.

Condition/Concern:
DTC U1000 or U1255 set current or history, with or without other DTCs

Recommendation/Instructions:
DTC U1000 Class 2 Data Link
DTC U1255 Lost Communications

These DTCs set when the control module does not receive a message that it was expecting from another control module, and does not know which control module did not send that message.

1. If the DTC U1000 or U1255 is set in history with other DTCs set current or history, diagnose the other DTCs first.
2. If the DTC U1000 or U1255 set current, this usually indicates a module that is currently not communicating or a configuration issue. For example, if the control module is configured for an option (ie: Onstar, Keyless Entry, Memory Mirrors, etc.) that the vehicle does not have, it may expect to receive a message regarding this missing feature. This would usually occur due to the control module being recently replaced and incorrectly setup.
3. When the DTC U1000 or U1255 is current, the module that is not communicating may not even be listed on the Tech 2 on the Diagnostic Circuit Check/Class 2 Message Monitor list.
4. If the DTC U1000 or U1255 has set in history without other DTCs, replacing the control module setting the DTC is most likely NOT the solution. The module that has set the code is looking for an input from another module that is not communicating. Since the module did not receive an input that it is expecting to see, it sets a U1000 or U1255 which indicates there was a loss of communications. Look at the customer's complaint (ie: intermittent, erratic tachometer operation); this will probably be a better indication of the control module that is the source of the concern. Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition.


Description-

DTC U1000

CIRCUIT DESCRIPTION
Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. When a module receives a message for a critical operating parameter, the module records the identification number of the module which sent the message for State of Health monitoring. A critical operating parameter is one which, when not received, requires that the module use a default value for that parameter. When a module does not associate an identification number with at least one critical parameter within 5 seconds of beginning serial data communication, DTC U1000 is set. When more than one critical parameter does not have an identification number associated with it, the DTC will only be reported once.

The class 2 serial data line on this vehicle is a star configuration. The following modules communicate on the class 2 serial data line:

* The audio amplifier (AMP), w/UQ7 and Y91
* The body control module (BCM)
* The communication interface module (OnStar(R)), w/UE1
* The digital radio receiver (DRR), w/U2K
* The driver door module (DDM)
* The electronic brake control module (EBCM)
* The generator battery control module (GBCM)
* The HVAC control module
* The hybrid control module (HCM), w/HP2
* The inflatable restraint sensing and diagnostic module (SDM)
* The instrument panel cluster (IPC)
* The memory seat module (MSM), w/AN3
* The passenger door module (PDM)
* The powertrain/engine control module (PCM/ECM)
* The radio
* The rear seat audio (RSA) controller, w/UK6
* The rear seat entertainment (RSE) assembly w/U42
* The rear wheel steering control module (RWSCM), w/NYS
* The remote playback device - CD player (CDX), w/U1S
* The transfer case shift control module (TCSCM), w/NP1/NP8
* The transmission control module (TCM), w/M74

DTC DESCRIPTOR
This diagnostic procedure supports the following DTC:
DTC U1000 Class 2 Data Link Malfunction

CONDITIONS FOR RUNNING THE DTC

* Voltage supplied to the module is in the normal operating voltage range of 9-16 volts .
* DTCs U1300, U1301 or U1305 do not have a current status.
* The vehicle power mode requires serial data communication to occur.

CONDITIONS FOR SETTING THE DTC
A node alive message has not been received from an unidentified module within the last 5 seconds after establishing class 2 serial data communication.

ACTION TAKEN WHEN THE DTC SETS
The module uses a default value for the missing parameter.

CONDITIONS FOR CLEARING THE DTC

* A current DTC clears when the malfunction is no longer present.
* A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

DIAGNOSTIC AIDS
When a malfunction occurs while modules are communicating, a lost communication DTC is set as a current DTC. When the modules stop communicating the current lost communication DTC is cleared but the history DTC remains. When the modules begin to communicate again, the module with the open fuse will not be learned by the other modules so U1000 is set current by the other modules. If the malfunction occurs when the modules are not communicating, only U1000 is set.

[NWTDIESEL]

For about a year now my instument cluster hasnt been working very well and sometimes doesnt come on for 5-10minutes after i start the truck. I wonder if this has something to do with it or if it finally went out?. Right now, i cant even get my truck to start. Im here at the shop with it trying to figure this out.

[NWTDIESEL]

Truck cranks over and over. After it sits it will start but then die. I now have codes
C0550
P1550
U1000
C0201
U1800

I will check all wires to ECM, FICM and all grounds tonight.

[Mike]

Truck cranks over and over. After it sits it will start but then die. I now have codes
C0550
P1550
U1000
C0201
U1800

I will check all wires to ECM, FICM and all grounds tonight.


DTC P1550

CIRCUIT DESCRIPTION
The fuel injector control module (FICM) activates the fuel injector-The engine control module (ECM) signals the FICM to turn ON the injectors through the fuel injector control circuits. The FICM self monitors the supply voltage whenever the ignition is ON. If the FICM senses a low voltage condition, DTC P1550 will set.

CONDITIONS FOR RUNNING THE DTC


•The ignition is ON.
•DTC U1800 or U2104 are not set.
CONDITIONS FOR SETTING THE DTC
The FICM detects low supply voltage.

ACTION TAKEN WHEN THE DTC SETS


•The control module stores the DTC information into memory when the diagnostic runs and fails.
•The malfunction indicator lamp (MIL) will not illuminate.
•The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
•The driver information center, if equipped, may display a message.
CONDITIONS FOR CLEARING THE DTC


•A current DTC Last Test Failed clears when the diagnostic runs and passes.
•A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
•Clear the DTC with a scan tool.

[blksmok]

C0550 - TSB Number: 01267F - Electrical System - Service 4wd light on no codes besides U1000 codes or c0550.
P1550 - Fuel Injector Control Module System Voltage
U1000 - Class 2 Communication Malfunction
C0201 - TSB Number: 040525002B - loss of communication with brake module
U1800 - Controller Area Network (CAN) Bus Communication

[PAC-MAN]

my buddies did the samething and it was the ficm. But only one thing in it went bad not the whole unit. But was enough to cause it to not to start, then start...die and then finally not do anything. Hope this helps?

[Ridge_Runner_Diesel]

Check the two bale connectors.

[delong_1]

Newly, if you need a FICM i have a spare i would sell ya, or let you borrow.

let me know.

[NWTDIESEL]

Thanks guys. I will get a FICM in the morning and try it. Im totally stumped, it has to be the FICM. I spent 3 hours cleaning the ECM connections, wire harness connections, FICM connections, TCM connections, all the injector harness connections. Truck wont even start at all now. Ill post up as soon as i try the FICM.

I really appreciate your guys help.

[NWTDIESEL]

I located a FICM from a wrecked truck and were going to get it right now. Ill switch em out and let you guys know.

[NWTDIESEL]

Just got done putting a new FICM in and it didnt work. I bled all the air out and checked all fittings. Im at a loss. It just cranks now and wont even try to start up.

FICM was from a 03 and my truck is a 04........?? An issue??

[Ridge_Runner_Diesel]

Reluctor wheel ?

[IdahoRob]

Look at your grounds. U1000 can be bad ground.

[RickDLance]

Also, IIRC, the early 03 is different. Midyear is when they updated the system.

[NWTDIESEL]

Jesus.

Its 7 deg outside. Im dropping it off at the dealer. What a great way to start off our family vacation....

Were on the road and i dont have great access to tools or parts.

I went over all grounds last night.

I guess its possible the reluctor wheel came loose but im sure i would have got a P0341 Camshaft Pos Sensor Circ Perf code right? Thats what happen to my friends dmax when he had the wrong reluctor wheel on his LB7.

[blksmok]

After the FICM swap did you clear the codes and are the same codes coming back?

[PAC-MAN]

This could get costly buying parts! Do you have access to a ECM? You said your on vacation. Where? Maybe someone can help in that area?

[MMLMM]

Last I talked to him they were loading it up and headed to the dealer....Guess we will see what happens now. That was 4.5 hours ago....

[tonydduramax]

This could get costly buying parts! Do you have access to a ECM? You said your on vacation. Where? Maybe someone can help in that area?
with so many issues I would think the ecm flakeing out jmo

[NWTDIESEL]

Yes i cleared the codes. I got it to start one time but it was idling real rough then it died. I have not checked the codes since.

A friend came with a trailer and took us to Albuquerque. Ill let you know what we find tomorrow :mad:

I have a spare ECM with me :thumb: we can throw it in the truck if thats what the Tech 2 finds to be faulty.

Im on the same page as all of you and luckily i have friends all over this side of the country loaning me parts. Cross your guys fingers for me.

[PAC-MAN]

Find the problem?

[NWTDIESEL]

I replaced the FICM, cleaned all the grounds and connections and still didnt start. All the fuses were checked and were good. It finally started and ran after i pinched all the fuse holders in tighter with a screw driver. One of the fuses were not making contact but its funny that it didnt pop or anything.

She is up and running! I must say the new(er) low mileage FICM seemed to make the truck run and idle smoother.

Thanks for all your guys help!

[emiller3]

Glad to hear its back going again.:thumb:

[S Phinney]

That is funny how all of a sudden it just starts freaking out Newly. I had a similar problem a couple years ago.

[ripmf666]

I replaced the FICM, cleaned all the grounds and connections and still didnt start. All the fuses were checked and were good. It finally started and ran after i pinched all the fuse holders in tighter with a screw driver. One of the fuses were not making contact but its funny that it didnt pop or anything.

She is up and running! I must say the new(er) low mileage FICM seemed to make the truck run and idle smoother.

Thanks for all your guys help!



So what did the dealer hit you for doing that -:t

[Reefermax]

wow, gotta love weird electrical problems, hope the vacation wasnt ruined :(.
while youre in abq, stop in and get a bite at casa bienavidez on the west side of paseo del norte, good food, eat lots of lotta burger and taco cabana :)

[NWTDIESEL]

Glad to hear its back going again.:thumb:

Me to! Thanks):h

That is funny how all of a sudden it just starts freaking out Newly. I had a similar problem a couple years ago.
Yea its very weird, i guess from all the vibration and taking the motor in and out a couple times loosened the fuses up? Idk. What was your situation?

So what did the dealer hit you for doing that -:t
Well my buddy that brought the trailer up to get me lives right next door to the chevy tech that looked at my truck. He couldnt find the problem either even when the Tech2 was hooked up. The tech looked at me truck for about 4-5 hours before he found the fuse issue but he only charged me for 1 hour. If any of you get stranded around Albuquerque go to Quality Chevrolet and ask for Mike Bacca. Vet nice guy and pretty smart too.

wow, gotta love weird electrical problems, hope the vacation wasnt ruined :(.
while youre in abq, stop in and get a bite at casa bienavidez on the west side of paseo del norte, good food, eat lots of lotta burger and taco cabana :)
Naw, the Vacation time is still good. Just got a little difficult with a 15mo old boy and my GF here with me. The temp was about 10* outside at 2am when i was swapping the FICM and trying to diagnose the electrical system.

[crazycrew]

Glad ya'll are back at it!! Still on vacation or headed home??

[NWTDIESEL]

Im in Durango, CO right now then i have to go back to Albuquerque this weekend. After that its either Montana, North Dakota or California lol

[crazycrew]

Damn, thta's one hell of a road trip!! Y'all be careful. Take some good pics!!

[Reefermax]

glad to hear you are back on the road :thumb: