LB7: I need help I turn the key and I get nothing no cranking of the engine

[lobocharlie]

I was tiring to start my 03 lb7 it was about 25 degrees and batteries went low then something made a noise and now when i turn the key I don't get any crank or turn of the engine It reacts like if it is in gear and try to start nothing. I bought new batteries they were not connected for 1 hour?

I have power to:
lights flashers radio wipers dome

I have no communications on the dash like the mileage
I have no glow plug



I check all fuses they are all good.
What happens when the ECM or TCM goes bad.

 

[McRat]

Is your Security Light on in the dash panel?

There is a component on your transmission that verifies you are not in gear. NSBU? or something like that. These often fail.

 

[lobocharlie]

I can still lock and unlock with the remote?
I only see the security thing when i use the remote. When I turn the key I don't see anything.

How do i reset the security?

 

[McRat]

You can reset the security with a Tech 2 or EFILive, but that's probably not it if you turn the key and the security light isn't on.

That transmission safety switch could be to blame. ECM's don't die easy, and a truck will start without a TCM.

 

[lobocharlie]

Where is the best place to purchase an ECM

That is what I was thinking. Where is the best place to purchase an ECM and not form the dealer? Thanks for your time.

 

[McRat]

Guessing at parts is pretty expensive.

You need to post something like:

New Mexico: Need Help!!!

We have several very smart Dmax hotrodders in your area.

A fresh ECM ain't cheap, and it might not fix your issue. If it was running, it's probably something minor.

 

[paint94979]

Guessing at parts is pretty expensive.

You need to post something like:

New Mexico: Need Help!!!

We have several very smart Dmax hotrodders in your area.

A fresh ECM ain't cheap, and it might not fix your issue. If it was running, it's probably something minor.

x2!!!

 

[Operator1]

Will it start in neutral instead of park? We had one at work today with a similar problem, it started right up in N.

 

[DBUSHLB7]

First off... Go Lobos! Haha being in the top 25 sure is nice.:thumb:

Brannex out on Brodway is decent for a used ECM. If you want a new one I can get a decent deal from the guys @ Galles Chevrolet. I live in Taylor Ranch. PM me if you need help.

 

[chevyburnout1]

Since you said you don't have any mileage readout on the dash, do any of the dash lights do their bulb check when you turn the ignition on? PRNDL readout showing anything? Does the Check Engine light turn on when first turning on the ignition? Quite possibly an ignition switch failing and not sending voltage to the ECM.

 

[lobocharlie]

I had nothing so:

I removed the ECM yesterday in the am because I was going to order one. I also plugged in the Block heater last night because it has been really cold.

SO when you asked about the lights I just walked out and put the key in turned the ignition and everything powered up.????
The security came on the gauges reset,The read out showed mileage.
So the switch is working.
I put the ECM back in and everything still displayed but no start.

I think I am going to try the 30 minute security reset and see where we go form there. I give an up date in a few.

Thanks for everyone's input in advance it is very much appreciated

 

[chevyburnout1]

Is the Check Engine Light turning on when you hit the key? If so go ahead and try that security relearn. Is there a line under the 'P' for the PRNDL readout?

 

[lobocharlie]

Is the Check Engine Light turning on when you hit the key? If so go ahead and try that security relearn. Is there a line under the 'P' for the PRNDL reado

I tried the security still no start.

The Check Engine is very very dim when i press the break it get brighter
what is the PRNDL? there is a dash line under the P in the trans selector window.
The gauges cycle all the way to the right then back to normal.

I have an old Snap on Mt2500 red brick and I use to be able to run the function test like A/C relay, Check engine light and it is not running any of them now.

 

[Bustedknuckles]

I guess ignition switch. If you put a ECM in on a guess you are NUTS. I'm a tech and there is a saying in the business. "Its never the computer" and ive seen it proven true often!

 

[MACKIN]

Have you tried bumping the starter when its keyed up like with screwdriver? What noise did it make?

 

[catman3126]

How does one do the security relearn?

 

[lobocharlie]

I put a remote start and it cranked freely. I turned on the Initiation then manually cranked and it just turns.

 

[chevyburnout1]

A dim Check Engine light I would look at power and grounds. Especially if this happened right after cranking on it a few times. Good possibility of ignition switch or a poor ECM ground. I can give you what terminals to check at the ECM if you want to check power and ground.

 

[lobocharlie]

That would be great. Do you really think it could be the switch? I am tiring to eliminate things as I go.

 

[chevyburnout1]

If you have a multimeter you can do a quick voltage check at the fuse block. Check to see what the voltage is at all the ECM/PCM and IGN fuses with the key in the on position and the batteries charged up. If the ECM can still communicate, someone with a scan tool could also look at the ignition voltage in the data display.