# 2000 silverado



## oldmn (Oct 16, 2005)

I have a weird electrical problem with my truck.
After it sits for a few day the battery was to low to start the truck (original Battery) so I replaced the battery.(600 CCA with a 950 CCA)
While doing this I notices when you open the door the gages would all drop down to zero. Close the door and when the dome lite goes out (About a minute) the gages are powered up again.
Lock the doors they power off for about a minute, them power on again.
Same with unlock.
I tried a different BCM (body control module) Besides the fact the truck would not run with it installed no change.:4-dontkno
How long it has been doing this? :4-dontkno
While I was working and running it daily it wasn't apparent.


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## Nutbuster (Mar 25, 2007)

I'll be interested to know what the techs say about this one! Wish I could help ya man!


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## qldit (Mar 26, 2007)

Good Morning oldmn, your description is similar to a high resistance problem in the supply line to those items.

If this were the case the current would favour the lamp and the voltage regulator that supplies power to the gauges could be inhibiting itself.

I would suggest firstly removing and refitting all fuses in the fuse panel, it could be caused by corrosion in a fuse spade or something lie that.

It would be easiest trouble shot by using a meter and monitoring that accessory line while powering other things and clarifying that situation.

Othere things that may cause this kind of problem are poor and loose connections, and possibly even earthing of lugs to body parts, but these would most likely be in the cabin.

Also carefully examine the connections at the battery that supply the voltage for all the accessory components etc. If you have "fusible links" also examine then at the same time. (these are usually located near the battery positive terminal.)

Sometimes it may be best to undo some connections and clean them before reconnecting them.

Others will have different ideas.

Cheers, qldit.


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## mack1 (Nov 27, 2007)

Hi oldmn,

You didn't mention if the key was in the ignition and if so, what position it was in. The key turned to 'on, bulb test, or start' will make the guages work, but if they are workiing with the key out or off, the problem would revolve around the ignition switch, I would think. 

Do you have wiring diagrams for your truck? 


If something is pulling current and draining your battery, you might disconnect the positive battery cable measure the current with a meter. If the current is too large for your meter, use clip leads and connect a small ohm resistor between the battery post and the cable end. Measure the voltage drop across the resistor to get the current draw using ohm's law. While connected in this fashion, it would be a good time to start pulling fuses one at a time to see if you could narrow down the leaking circuit. You might get lucky and find it quickly (or not) :grin:

Best wishes,
Mack1


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## oldmn (Oct 16, 2005)

Testing at this point is pointing to the BCM (Body Control module) 
$350 + $100 to program it. It is the only thing that has input to both circuits.


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## qldit (Mar 26, 2007)

Good Morning oldmn, I would suggest metering the voltage input to that module, if it has a plug try removing and refitting it, othewise you may be able to measure the voltage at the underdash fuse block.

Sounds like it may well be a control module problem, that is a shame.

Try not to be in a situation where you obtain a replacement and find the problem persists.

Best of luck, those modules use solid state switching and have reduced the load which was previously on an ignition switch accessory contact.

That symptom may well be the actual supply to the module though which most often is a different circuit.

Cheers, qldit.


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## mack1 (Nov 27, 2007)

Hi oldmn,

My book shows the locks and lamps tied to the BCM, but the guages are not. 
I have a 2004 silverado and my Haynes book covers 1999 through 2005. You may have a better book.

Anyway, I'm kinda like qldit, wouldn't want you to spend $450 on a BCM and that not be the actual problem.

Regards,
Mack1


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## Slaton (Apr 23, 2008)

When you replaced the battery, was there any corrosion present at the positive terminal? You may have to remove the cable terminal sheath and clean the connection. Also check to see if corrosion is present in the actual cable below the terminal. I have run into numerous electrical concerns due to corrosion of these vehicles battery terminals.


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## oldmn (Oct 16, 2005)

I always replace the cables with the battery. (old habit)


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## RIGHTE0US (Jan 7, 2008)

can you open the rubber boot in the door jamb?...if so, look for broken wires or wires that seem very rubbery in certain spots. If you have broken wires they may be contacting each other and causing this problem


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## RIGHTE0US (Jan 7, 2008)

and by the way, be sure your ground strap from the engine to the battery is good.


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