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sprinkles08
sprinkles08, ASE Certified Technician
Category: Chevy
Satisfied Customers: 21602
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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My alarm does not unlock the doors. The vehicle will not

Customer Question

My alarm does not unlock the doors. The vehicle will not start. I have codes of U1000, U1064, and C0379. What is the possible fix.
JA: Thanks. Can you give me any more details about your issue?
Customer: The DIC is showing Service 4WD. I just had all of the actuators and Encoder with motor replaced. With the alarm I cut the wire for the kill switch relay and the problem went away for a while. The instrument panel lights up but noting happens when I try to start the vehicle. I listened in the engine compartment by the large relays and I hear one of the relays click after I try to start the vehicle.
JA: OK got it. Last thing — Chevy Mechanics generally expect a deposit of about $18 to help with your type of question (you only pay if satisfied). Now I'm going to take you to a page to place a secure deposit with JustAnswer. Don't worry, this chat is saved. After that, we will finish helping you.
Submitted: 8 months ago.
Category: Chevy
Expert:  sprinkles08 replied 8 months ago.

Hello and welcome to JustAnswer!

U1000 sets in a module when it isn't able to communicate with the engine controller. This should be related to the engine not starting. If the ECM isn't awake then the engine won't be able to start.

Have uses been checked?

What year and model is the vehicle?

Customer: replied 8 months ago.
I have checked all of the fuses. I have a 2003 Chevrolet Silverado Z71 4X4. Some times I disconnect the battery and the next day the vehicle is running again.
Customer: replied 8 months ago.
Should I be concerned?
Expert:  sprinkles08 replied 8 months ago.

You have no fuel pressure or spark, correct?

Customer: replied 8 months ago.
I have fuel pressure and spark. It does not want to turn over when you try to start it.
Expert:  sprinkles08 replied 8 months ago.

Can you elaborate on that? You can't have spark if the engine doesn't turn over.

Customer: replied 8 months ago.
The engine has to turn over to start when this problem is not happening the vehicle starts right away. I was driving it yesterday. The fuel pump has been replaced just recently.
Expert:  sprinkles08 replied 8 months ago.

What specifically happens when you move the key to the crank position?

Customer: replied 8 months ago.
The lights come on on the cluster (instrument panel) there is no noise when you try to crank the engine. It is like the alarm has not sent the signal to the kill switch.
Customer: replied 8 months ago.
May be the ignition switch. This happens about one a month.
Expert:  sprinkles08 replied 8 months ago.

What module was the U1000 set in and does it return after clearing?

What brand and model of alarm is on the truck?

Customer: replied 8 months ago.
Crime Guard 850 i4 alarm. I do not understand what you mean by what module the U1000 set in and does it return after clearing. How does it clear.
Customer: replied 8 months ago.
I got three codes U1000, U1064, and a C0379. I cleared all of the codes but the U1000 does not clear. Plus the transfercase motor and encoder along with the front axle actuator were replaced a year ago.
Customer: replied 8 months ago.
The U1000 and C0379 codes do not clear.
Customer: replied 8 months ago.
Can we continue tomorrow? I need to go to bed because I have to work tomorrow.
Expert:  sprinkles08 replied 8 months ago.

Yes, we can continue tomorrow.

When you reply back, what module are you entering with the scan tool when finding the U1000?

Customer: replied 8 months ago.
I am connecting an OBDII tool to the connector under the dash by the Emergency Brake Pedal.
Expert:  sprinkles08 replied 8 months ago.

Correct, but I'm trying to determine what module this is set in. Depending on build there could be upwards of 20 modules on the vehicle and I'm trying to determine which module isn't able to communicate with the PCM.If you're not picking modules from a menu (it sounds like you're using a code reader rather than a scan tool) then you won't have a way of knowing.

Customer: replied 8 months ago.
I'm using a scan tool. OCD 3111. I don't have the equipment that you are talking about. Good Night I will talk to you tomorrow.
Expert:  sprinkles08 replied 8 months ago.

It's a code reader but does have access to more than just the engine controller, it looks as though you should be picking from the menu for the couple modules it's capable of communicating with.

Customer: replied 8 months ago.
I just got home from work. I do not know how to diagnose form each individual module and I am not sure if it has that capability. Ok I have the following codes: U1000 SRS $58; U1000 XFER $1A; C0379 XFER $1A; and U1064 ENG $10. I hope that this is what you a talking about. Oh my scan tool is a OTC 3111 OBDII and ABS Scan Tool
Expert:  sprinkles08 replied 8 months ago.

It looks like the U1000 is set in the airbag module.

Does the fuel pump run when the key is first turned on at this time?

Customer: replied 8 months ago.
No
Expert:  sprinkles08 replied 8 months ago.

Have the PCM powers and grounds been tested?

Customer: replied 8 months ago.
How do I test the Power and grounds on the PCM. I also need to know the pin layout. I will be tomorrow before I can test them.
Customer: replied 8 months ago.
Need to know the location of the PCM.
Expert:  sprinkles08 replied 8 months ago.

The PCM is in the engine compartment to the left of the fan shroud.

A test light will be used to test the powers and grounds.

The pink wire in connector 1 (blue) pin 75 and the pink wire in pin 19 should have power with the key on.

The orange wires in pin 20 and 57 should should have power all the time.

The black/white wires in pins 1 and 40 should have ground.

Customer: replied 8 months ago.
I will check this tomorrow. Goodnight
Expert:  sprinkles08 replied 8 months ago.

Have a great night!

Customer: replied 8 months ago.
Interesting. I just went out and disarmed the alarm on my Silverado. I have not tested anything or done anything. I tried to remote start the vehicle and it started right up. Any ideas?
Customer: replied 8 months ago.
I would really like to know what the problem is.
Expert:  sprinkles08 replied 8 months ago.

Does it remote start but not start with the key?

Customer: replied 8 months ago.
It is also starting with the key.
Expert:  sprinkles08 replied 8 months ago.

You'll have to wait until the problem returns to begin testing then.

Customer: replied 8 months ago.
When that happens do I respond to this?
Expert:  sprinkles08 replied 8 months ago.

Yes, if you need more help you can reply here.

Customer: replied 8 months ago.
Okay, Thanks.
Expert:  sprinkles08 replied 8 months ago.

You're welcome!

Customer: replied 8 months ago.
I spoke too soon. I ran three errands with the Silverado. Then it went back to not starting. Tested the pins in the PCM pins 1 and 40 show continuity. Pins 20 and 57 have 12.14 volts DC with the key off. Pin 19 has 12.14 volts DC with the key on. Pin 57 has 20 to 35 millivolts DC with the key on.
Expert:  sprinkles08 replied 8 months ago.

Did you mean that pins 1 and 40 had ground?

You mentioned pin 57 having power but then not having power?

Customer: replied 8 months ago.
pins 1 and 40 had ground. Pin 57 had low voltage from 20-35 millivolts DC.
Expert:  sprinkles08 replied 8 months ago.

You have a wiring issue then. Pins 57 and 20 are fed by the same fuse. The circuit leaves the fuse as one and then splits into two wires, coming into the PCM on these two separate terminals. If you have power on 20 when there is none on 57 then you have an open ciruit between the fuse box and PCM pin 57.

Customer: replied 8 months ago.
Ok so which fuse feeds pins 20 and 57.
Expert:  sprinkles08 replied 8 months ago.

PCM B.

Customer: replied 8 months ago.
Where is that
Expert:  sprinkles08 replied 8 months ago.

In the fuse box under the hood.

Customer: replied 8 months ago.
I told you the wrong pin. I have 20-35 millivolts DC on pin 75 with the key on. Sorry!!!
Expert:  sprinkles08 replied 8 months ago.

While power isn't present there check for power at the IGN0 fuse in the dash and see if it's present there.

Customer: replied 8 months ago.
I have low voltage on ING0.
Expert:  sprinkles08 replied 8 months ago.

What is the voltage on the white wire at the ignition switch with the key on?

Customer: replied 8 months ago.
3.4 millivolts DC
Expert:  sprinkles08 replied 8 months ago.

What is the voltage on the red/white wire?

Customer: replied 8 months ago.
11.84 volts DC
Expert:  sprinkles08 replied 8 months ago.

The ignition switch has failed.

Customer: replied 8 months ago.
I have a problem. I bought a new ignition switch and installed it. I still have the same problem. I ohmed the switch where the red/white and white wires would be with the switch in the on position. It shows open. Am I doing something wrong? I have exchanged two switches already.
Expert:  sprinkles08 replied 8 months ago.

Do you have the VIN?

Customer: replied 8 months ago.
I do but I am not sure that I should put it out on the internet. 1GCEK19T63E380259
Expert:  sprinkles08 replied 8 months ago.

Is there power on the solid red wire?

Customer: replied 8 months ago.
It has 3.4 millivolts DC. The same as the white wire.
Expert:  sprinkles08 replied 8 months ago.

Is the 40 amp IGN A fuse under the hood good?

If so, does it have battery voltage?

Customer: replied 8 months ago.
Ignition A and B have 12 volts DC and both fuses are good.
Expert:  sprinkles08 replied 8 months ago.

Did you verify that power is still not present at the ignition switch while it's present at the fuse?

Customer: replied 8 months ago.
With the key off I have 11.48 volts DC. With the key on I have 3.4 millivolts DC.
Expert:  sprinkles08 replied 8 months ago.

It sounds like you have voltage drop in the circuit due to corrosion then. Battery voltage is present until the circuit is loaded. If you used a test light you should see when a voltmeter shows 11.48v it won't actually light a bulb.

The problem is either internal in the fuse box or in the wire between there and the ignition switch. The next step will be to check the wire as it leaves the fuse box, I'm away from my wiring diagram until this evening and can get the location then.

Customer: replied 8 months ago.
I have to go to work in a little while but I am curious if you think that the alarm could be causing this problem
Customer: replied 8 months ago.
I will also need to know how to disassemble the fuse box to get to the wiring
Expert:  sprinkles08 replied 8 months ago.

It's not an alarm problem unless the alarm is wired to interrupt power on this circuit.

Customer: replied 8 months ago.
I think that it could be. There are wires sliced into the ignition switch wires and the AU-Socket and relay for the starter interrupt.
Expert:  sprinkles08 replied 8 months ago.

You'll need to physically inspect this wire to see if it has been cut and wired into and out of the alarm module. I don't know why an installer would have done so but alarm installations are often done poorly.

Customer: replied 8 months ago.
I wish that you could see this mess
Expert:  sprinkles08 replied 8 months ago.

You can upload a picture using the paperclip icon in the toolbar.

If you don't care about the alarm and it's that bad then you might consider removing the alarm and wiring, returning all connections and wiring back to factory.

Customer: replied 8 months ago.
I am pointing to the red wire and its spliced into the alarm. But I'm not sure how its spliced into the alarm.
Customer: replied 8 months ago.
There is a module that is tied into the red and white wire also that goes into the ignition switch
Expert:  sprinkles08 replied 8 months ago.

Is the red wire cut then so power flows from the wire into the module, the module back to the red wire and then on to the ignition switch?

Customer: replied 8 months ago.
I have 11.68 volts from the red wire, but I still have milli volts from the white wire. And looks like something is tied into the white wire
Expert:  sprinkles08 replied 8 months ago.

Do you have an incandescent test light? The voltmeter can get you into trouble here.

Customer: replied 8 months ago.
There is a orange wire spliced into the white. There was another color of wire also spliced with the white wire and that wire was loose and the white wire is burnt. Still low voltage on the white wire
Expert:  sprinkles08 replied 8 months ago.

The red wire is what we're currently dealing with. If there is no power on the white wire it's a failed ignition switch or lack of power on the red wire from the IGN A fuse.

Customer: replied 8 months ago.
Where does the yellow wire go into the ignition switch
Expert:  sprinkles08 replied 8 months ago.

You're currently concerned with the red power feed wire to the switch.

Customer: replied 8 months ago.
The alarm has a kill switch wired into the ignition wiring I think that since the alarm is disabled that the kill switch is keeping the vehicle from starting. One side of the kill switch is spliced on to the yellow ignition wire. Power for the alarm was being drawn from the red and white and the red ignition wires. Since I disabled the alarm I have to undo the alarm wiring. The kill switch is also tied into the other half of the yellow wire which is the starter wire.
Customer: replied 8 months ago.
The white ignition wire has continuity to IGN0
Customer: replied 8 months ago.
I cannot do anything with voltage until I get the wiring covered up
Expert:  sprinkles08 replied 8 months ago.

The red power feed wire to the ignition switch is the circuit you're currently concerned with.

If the alarm installation is poor or if you don't want/need the alarm I would recommend removing it and all of it's wiring.

Customer: replied 8 months ago.
I have completely removed the alarm. I have 11.30 volts on the red wire 3.4 milli volts on the white wire. Battery Voltage is 11.34 volt. I can't keep replacing the ignition switches
Expert:  sprinkles08 replied 8 months ago.

You're going to need to use a test light for accurate results.

Customer: replied 8 months ago.
The problem that I have is that you are saying that the ignition switch is bad. The last switch that I got was from the Chevrolet dealer. I also do not understand what the make and break is on the ignition switch. I should be able to ohm it out to tell if it is good.
Customer: replied 8 months ago.
I am going to exchange the ignition switch tomorrow and try another new switch. I am going to bed. I have to work tomorrow also. Good night.
Expert:  sprinkles08 replied 8 months ago.

That was a couple days ago, we've been diagnosing a power feed issue to the switch. A voltmeter or testing resistance it's going to help. You need to load the circuit with a bulb and see if the red wire will light an actual bulb. If not then there is a wiring issue between the fuse box and switch or the problem is in the fuse box.

Customer: replied 8 months ago.
Ok there are three wires that are connected when the ignition switch is turned on. The red which has full voltage when the key is turned off. The white wire which has no voltage when the key is turned off. The orange wire that has no voltage when the key is turned off. When the key is turned on is when the problem arises. The red, white and orange wires have less than one volt. We have beaten the red and white wires to death. I think that we need to look at the orange wire. Where does the orange wire go. What fuses.
Expert:  sprinkles08 replied 8 months ago.

The white wire not having power with the key on is why the PCM isn't awake. If this wire doesn't have power it's because of a lack of supply to it or the ignition switch has failed, and that's obviously not the case.

How did you determine the red wire has 'full voltage'?

Customer: replied 8 months ago.
This does not help. I understand what you are saying but you do not seem to understand what I am asking. I need to know what fuse(s) the orange ingnition wire goes to. The drop in voltage can be in the orange ignition wire. There can be a short in the orange ignition wire.
Expert:  sprinkles08 replied 8 months ago.

I do understand what you're asking but jumping around and investigating other things without repairing the known issues isn't moving in a positive direction. There are multiple circuits through the ignition switch that share the same power feed from the red wire. I cannot proceed until that circuit is repaired.

Customer: replied 8 months ago.
I found the connector for the orange and white wires at the back of the fuse box. I unplugged it an checked for power. The voltage on both the white and orange wires went up to the battery voltage. I am not investigating multiple problems there is a voltage drop and wherever the orange wire goes us causing it. Please tell me where the orange ignition wire goes. What fuses does it go to.
Expert:  sprinkles08 replied 8 months ago.

The voltage drop is on the power feed circuit to the ignition switch from the IGN A fuse.

Your question is open for others. If another expert wishes to help they will respond here automatically.

Customer: replied 8 months ago.
I looks like you and your site need to get ready to refund my money and cancel my subscription since you do not want to help me resolve my problem.
Customer: replied 8 months ago.
Plus you have caused me to spend money on parts that were not the solution. If I had the electrical diagrams I would fix this problem on my own. When you do not answer my question doesn't that undermine the name of the site? Or you don't know the answer.