Brad30
Forum Newbie
Posts: 7
Reg: 07-27-12
|
 07-27-12 06:02 PM - Post#2252810
My 1984 Chevy K10, w/ 305 & 700R automatic, shows a drop in voltage when I shift into four wheel drive. I have been unsuccessful in finding the cause. Increase in throttle has no affect until the wheels stop turning. Several years ago I converted from a carburetor to tbi system. Did not have this problem until now. Any help with this is appreciated.
|
|
Yenkonova
Senior Member
Posts: 731
Loc: Pueblo, CO
Reg: 07-23-04
|
07-27-12 07:40 PM - Post#2252832
In response to Brad30
Is this voltage loss just viewed on the gauge in the dash or have you watched it with a voltmeter at the battery or alternator?
Rob Z.
'69 Nova (quick one)
'75 K5 Blazer (slow one)
'97 S10 2wd faux-SS (Daily Driver)
'04 TrailBlazer (Grocery getter)
|
|
Brad30
Forum Newbie
Posts: 7
Reg: 07-27-12
|
 07-28-12 05:39 AM - Post#2252919
In response to Yenkonova
With truck running, on jack stands, in four wheel drive, in gear, wheels turning there is 14.62 volts at the battery, 14.83 at the alternator, and 10.25 in the cab wiring. Lights (interior) begin to dim. This does not change if I add throttle and show a speedometer reading of 30 mph.
Condition does not exist while performing the same test (on jack stands) but in two wheel drive. However when on the ground and driving, in my parking lot or on the highway, in 2 wheel drive I get the same results. I have checked all connections, detached the wires to the transmission and transfer case and unhoked the VSS, and performed this same test. Earlier vehicle let me down on highway with dead battery, installed new battery, had the alternator tested, no change. Thanks for responding. Any idea's.
|
 Vaughn
"11th Year" Gold Supporting Member
Posts: 13554
Loc: Colorado Springs, CO
Reg: 08-08-04
|
07-28-12 07:57 AM - Post#2252944
In response to Brad30
The only thing I am aware of that switches on during 4wd is the 4wd indicator light.
However, to isolate where your current drain is - put the truck in 4wd.
Now, you can either pull fuses while watching the voltage gauge - or you can shut the truck off, disconnect the battery and stick an ammeter in between the disconnected terminal and the battery - then pull fuses while watching the ammeter. The ammeter method is more accurate, but the voltmeter is easier to do.
By pulling fuses, you isolate the circuit that is shorting out. After finding out which circuit has the short, you follow the wiring in that circuit to find the short.
|
Allan In NE
Contributor
Posts: 903
Reg: 12-27-11
|
07-28-12 08:07 AM - Post#2252947
In response to Brad30
You've got a bad body ground circuit.
System voltage should be the same front bumper to rear.
When you put the rig in 4x4, the system is trying to make ground going the long way around thru the shifter/engine block/transmission.
Allan
| Lifelong GM automatic transmission specialist |
|
Brad30
Forum Newbie
Posts: 7
Reg: 07-27-12
|
07-28-12 08:31 AM - Post#2252953
In response to Allan In NE
just now I have disconnected the circuit to the trannsmision lockup and the indicator circuit to the transfer case and have removed the indicator socket from the back of the instrament cluster. with all this done I still get the discharge when shifting the fwd floor shifter while the transmission is in gear and the wheels are turning. Just moving this one lever does it. shift it back into 2 wd and all is fine. Mystery. 
|
Brad30
Forum Newbie
Posts: 7
Reg: 07-27-12
|
07-28-12 09:32 AM - Post#2252962
In response to Brad30
Added an additional ground to the cab and all is fine. too simple. At least I have inspected all the connections and cleaned them up. Thanks for your help. 
|
 gchemist
Senior Chevytalk Moderator
Posts: 20826
Loc: Austin, TX 78748
Reg: 05-09-00
|
07-29-12 05:00 AM - Post#2253240
In response to Brad30
Welcome to the site.
I noticed you changed fuel deliver over to TBI. Nice!!
Electrical trouble shooting is not my thing. I'll move your post over to a larger forum. Someone there may notice an electrical problem.
'83 Silverardo XST - ZZ4 powered
'96 GMC Jimmy LS |
|
MikeB
Senior Member
Posts: 9388
Loc: Plano, TX
Reg: 08-28-03
|
07-29-12 07:35 PM - Post#2253506
In response to Allan In NE
Good call, Allan. 
Real Hot Rods have a Clutch!
1955 210 2dr: 327, Brodix IK180 heads, Jones cam, Muncie M20, Wilwood front brakes
1969 C-10 pickup: 350, TH350
My car pictures
|
|
|
Gain extra benefits by becoming a Supporting Member 
drtyler (4)
