Voltage drop

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LakotaWolf

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Hey folks.

I just bought an '06 Montana last week. Yesterday, I opened the power windows to get the heat out, but I couldn't raise them back up. I did some voltage checking and it shows 3 volts at the circuit breaker. As I was starting the engine to do voltage checks I noticed the cranking speed kept getting slower until finally it just one click, the smell of hot wires and a small puff of smoke coming from the starter area. The battery shows 12.4 volts. I even tried to charge the battery, and it shows full charge after about 10 minutes. I checked all the lights, radio, fan motors. Everything else works fine. The problems are no crank, and only 3 volts at the window circuit breaker. Anyone got any input on this?
 
you saw smoke, you burned/melted a wire, possibly a fusible link.
 
I looked at a schematic for the 2006 Montana. It doesn't show a fusible link anywhere in the starter system. I'm beginning to think there's a problem in the solenoid. I tried to start it and did crank a few slow turns, but it sounded like the starter hung up and didn't pull the gear back after I released the key. I'm still trying to figure if the power windows and the start trigger are on the same power wire.
 
Ok, figured out one problem. I pulled the fuse, ran a jumper wire from the battery to the cold side of the fuse socket. I pulled the plug from the drivers side window switch and ran jumper wires to the plug. Both sides up and down with no problems....Bad switch. Now the low voltage problem has gone from 3 volts to 5 volts. Still a problem there.
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Did some more voltage checking this afternoon. I found low voltage, (5 volts) on four fuses. Both ELC fuses, steering wheel illumination, and the power windows circuit breaker. Two questions... What is the ELC, and what is RAP??? I also noticed that while I was checking fuses with the key in the run position, the battery voltage dropped from 12.4 to 11.2 in about 20 minutes. Is this normal?
 
Hi !
Retained accessory power (RAP) is a power mode that permits the operation of some accessories for up to 10 - 20 minutes after the ignition switch is turned OFF. The RAP power mode is enabled by the body control module (BCM).
The BCM controls the RAP relay . The output of the relay is used to supply battery voltage to the windshield wipers and power windows. The RAP relay also provides voltage to the windshield wipers and power windows when the Accessory and Run power modes are selected.
(ALC) auto level control - air compressor , inflator relay , sensor , trailer.
I will express my opinion : or...
- you have problems to a bad starter that was causing the battery cable to short out on the housing of the starter.
or...
- That's the main Ignition Relay.
 
Last edited:
Hey Serge, thanks for the quick reply.

Ok, now RAP makes sense. The book and the fuse panel has it listed as Accessory Power, and not RAP. I also discovered, after much searching on the net, that ELC stands for Electronic Level Control. So now I have the low voltage narrowed down to four locations. The two ELC, steering wheel illumination, and power windows. I'm beginning to think the starter problem is a separate issue. If the battery wire to the starter was shorting, it would affect voltage throughout the entire system. There is the possibility that the wire that runs from the ignition switch to the solenoid is a fifth location and it's not pulling the solenoid plunger back far enough to make a solid connection with the starter contacts. I'll check that out today and get back to everyone on this.
 
Finally got some free time to work on the van today. Last week I charged the battery all day. The next morning the battery was dead. I disconnected the ground cable, recharged the battery, and it's held for three days. Today, I did an amp draw test. With the meter between the neg battery post and the neg cable, I showed an initial draw of over 3 amps, (interior lights). When the lights went out it dropped to 0.310 amps. After a few minutes it would drop to 0.130 amps. I did this test several times. A few times it dropped to 0.009 amps, but went right back up to 0.130 amps. Is this enough amperage draw to drain a battery in 8-10 hours?
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Hi!
At first - Your vehicle should be tested at around .15MA to .24MA. The maximum current flow is - 50 MA.
Secondly - on to the parasitic draw test...engine off.. drivers window down.. all lights off...
Disconnect one side of the battery.. turn the digital volt meter to 10 or 15 amp DC setting.. you will have to replug one of the leads in the meter face.. then hook the amp meter across the gap you have made by unhooking one side of the battery... one wire to the post... one wire to the disconnected terminal..
Expected reading is 0.020 or 0.025 amps... post what readings you get... there are several computers onboard that need full time power.. there are several circuits that may draw power when the key is off.. when they have failed...
...i usually open the door.. pull the dome light fuse... see if the draw vanishes...
if it is still there.. start pulling the fuses one at a time... checking the draw... each time...
 
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