Truck Won't Start - Disconnect Battery And It's Fine

splat10 · August 5, 2009

So i've had this issue a few time now. The first time i spent hours trying to figure out what was going on until i disconnected the battery and it was fine. Now that I know it is just annoying because I have to wait 10 minutes for the ECU to reset.

I do have a compustar remote starter also. (99 NBS silverado LS, Z71)

What it's doing is this. I put the key in to start it and turn, the dinger dings once, and i get nothing. The gague may jump all over the place for a few seconds, and i can hear all my relays clicking like crazy. The security light in the info center is very dimmed and all the lights are light it's dumping power somewhere since they are all very dim.

It's never happened to me at a time when i didn't need to be somewhere or at home so i haven't been able to dig into it. Twice it's happened while sitting all day at work, and one after a five minute trip into a store so not a hot/cold interior/engine issue that i can tell.

Sounds like ECU or remote start to me but don't know where to start.

Please help

belchfire · August 5, 2009

How old is your battery?

ShoddyHog · August 5, 2009

How old is your battery?

Also check both wires for corrosion and contact. Check all grounds you can find as well.

splat10 · August 5, 2009

well i'm pretty sure it's a loose connection on my remote start module because when it happened today i reached under the dash and grabbed a handful of wires and jiggled and all was fine. Last time i played with those wires a lot and no luck but today was a different story. I'll have to dig into it some more soon.

definately not the battery

grimmysnr · August 6, 2009

Turn your attention to the remote start. I have a viper that GM installed and sometimes messing with the battery can send my truck into a tangent. Pulling the positive on the battery calms her down and everything is cool again.

splat10 · August 28, 2009

ok so it happened again yesterday and i couldn't get it to come back for a long time. I tore the whole dash apart looking for frayed or disconnected wires and didn't find anything. I unplugged the remote start module and it didn't change anything.

There's a plastic delco box under the dash with three harnesses going into it (brown connector, blue, and purple) that seems to be the in area when i'm successful wiggling wires.

I did the negative battery cable (which has worked before) and no improvement after 15 minutes. But when i did the positive cable (it was hot to the touch) it fired right up.

I'm starting to think it's my ECU. Is there a way to test the ecu? How much is a new one? Once it starts it's fine.

Another (possibly related) issue is that i went to pass someone yesterday and stopped on the gas. I'm now hitting the rev limiter at 4,000 RPM. At first i though it was the tranny slipping but it's not, Then i thought it was the fuel pump starving (since it went bad earlier this week), Then i was able to recreate it yesterday and it was definately a rev limit type action.

I'm stumped here and the truck might end up in the crusher soon if i can't figure this out.

ShoddyHog · August 28, 2009

At the very least, I'd either take it to a dealer or a LSx performance shop and have them flash the stock tune again. Something sounds messed up with the tune.

Disclaimer: Just saw you have a '99. Not sure if they can flash those tunes like the new ones. I'm assuming they can.

Gerry

splat10 · August 28, 2009

searching found something on NSBU. Could that cause this screwy reaction?

splat10 · August 28, 2009

another tidbit. If i put the key in the accessory position it radio will work fine. going forward to on the radio and everything else wont work.

I put the flashers on with the key out and the relays for the door locks were going nuts. But when i put the key back in the relays stopped. All very weird.

I'm now leaning to either BCM or ignition switch, especially since the above-mentioned wires that i'd grab and sometime "fix it" were the ones connected to the BCM (assuming that's what that black delco box i described above is.

ShoddyHog · August 28, 2009

Man, um...

splat10 · August 29, 2009

i'm thinking more like this but you idea might work too

ShoddyHog · August 29, 2009

I feel for you man. For the last six years I had starting problems with my Bonneville. Last winter (y'know when it is pitch black going to work), all of a sudden in bumper to bumper traffic, all the dome lights would come on, and the door open buzzer would go off. I'd then have to open the door while still moving to get it to shut back off. I belive the BCM was about dead in that thing.

Good luck.

Gerry

bossier62guy · August 29, 2009

I did the negative battery cable (which has worked before) and no improvement after 15 minutes. But when i did the positive cable (it was hot to the touch) it fired right up.

Your positive cable shouldn't be "hot" to the touch.....Did you check the cable for internal corrosion? Probably caused from a leaking terminal in the past.

ShoddyHog · August 29, 2009

I did the negative battery cable (which has worked before) and no improvement after 15 minutes. But when i did the positive cable (it was hot to the touch) it fired right up.

Your positive cable shouldn't be "hot" to the touch.....Did you check the cable for internal corrosion? Probably caused from a leaking terminal in the past.

+1 I had to have that cable replace on my Bonnie. It had side terminals, and had corroded down into the wire...couldn't see it because of the wire casing.

splat10 · August 30, 2009

I had a lot of corrosion on the positive terminal and i cleaned that up good and put some of the red goop on it. We'll see if it happens again. The more i think about it it seems like a voltage issue on the computer.