1984 Battery Drain + misc issues
Thread Starter
Cruising
Joined: Apr 2005
Posts: 10
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1984 Battery Drain + misc issues
I'm a new owner of a 1984 Corvette and am working on a fewe issues:
1) The battery drains overnight - we traced the short to one of the main red wires coming up from the battery and going into the firewall on the lower wire loom, driver's side. We separated the wire and it's showing a partial ground on the part groing into the car from that spot. We're suspecting something like a bad ignition switch. Alternator checks out ok.
2) High Idle - We checked timing and for vacuum leaks and the idle is now about 800 rpm.
3) Engine code 21 - Throttle positioning Sensor code comes up, what should we check to fix this?
Any help greatly appreciated.
1) The battery drains overnight - we traced the short to one of the main red wires coming up from the battery and going into the firewall on the lower wire loom, driver's side. We separated the wire and it's showing a partial ground on the part groing into the car from that spot. We're suspecting something like a bad ignition switch. Alternator checks out ok.
2) High Idle - We checked timing and for vacuum leaks and the idle is now about 800 rpm.
3) Engine code 21 - Throttle positioning Sensor code comes up, what should we check to fix this?
Any help greatly appreciated.
Racer
Joined: Oct 2004
Posts: 286
Likes: 1
From: Washington DC
The first thing to do is to buy a factory service manual. It will have the diagnostic chart for your TPS, etc. You could have a bad TPS, bad supply voltage to the TPS, or a misadjusted TPS (if yours is the adjustable type.)
As far as the parasitic load, there's an easier and more precise way to locate it. Connect a DVOM in series with the battery (@ the cable) Make sure all your accesories are off (including interior lights, etc) See what your base amperage is, and then start pulling fuses, until you get a noticeable drop. The fuse you pulled that caused the drop is the faulty circiuit. Then you'd go to your service manual, and start looking for components that share that fuse.
As far as the parasitic load, there's an easier and more precise way to locate it. Connect a DVOM in series with the battery (@ the cable) Make sure all your accesories are off (including interior lights, etc) See what your base amperage is, and then start pulling fuses, until you get a noticeable drop. The fuse you pulled that caused the drop is the faulty circiuit. Then you'd go to your service manual, and start looking for components that share that fuse.
Thread Starter
Cruising
Joined: Apr 2005
Posts: 10
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Thanks. I think I do have a adjustable TPS.
I was using a test light between the posivite battery terminal and the positive battery post. We pulled the fuses one by one but the light never dot dimmer or went out.
The digital volt meter sounds like it's more accurate and I have one of those.
The car runs fine at upper rpm, the code error does not come up unless it's idling.
Could a bad ground cause a lot of these issues?
I was using a test light between the posivite battery terminal and the positive battery post. We pulled the fuses one by one but the light never dot dimmer or went out.
The digital volt meter sounds like it's more accurate and I have one of those.
The car runs fine at upper rpm, the code error does not come up unless it's idling.
Could a bad ground cause a lot of these issues?
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
There are some 8 wires on the jump start terminal and each of these wires has a fusible link. They go to the RH & LH headlight door relay, blower control module or blower relay if manual a/c controller, 2 go to the alternator, headlight switch and ctsy clk fuse, fuse block and the auxiliary fuse block. This info is from my 87 electrical service manual and for better accuracy you need to get a manual for the 84, but I think it will be essentially the same.
It sounds like you have found the wire the leakage current is going and you need to trace where it goes to further locate the source of leakage current.
It sounds like you have found the wire the leakage current is going and you need to trace where it goes to further locate the source of leakage current.
Last edited by jfb; Apr 3, 2005 at 06:55 PM.
Thread Starter
Cruising
Joined: Apr 2005
Posts: 10
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I checked the voltage on my TPS with ignition on and also with engine running and it was 5.10 volts. It did not change when I tried to adjust it by loosenting the set bolts and did not change when I increased throttle. Sometimes the car starts and idles fine with no check engine light and then it stumbles and goes "rich" like and runs poorly, then the check engine light comes on. When the check engine light is out and I pull the connection to the TPS while running it comes on each time.
Also I found that I have 12.48 volts measured from the negative battery post to the negative cable going to ground (not good). I get the same voltage measuring the same thing between the positive battery post and the positive terminal. I pulled each fuse and watched my volt meter but it never dropped so it much be somthing else. I have isloated the red main wire that is connected to this problem but have not figured out which wire it is.
I did change the engine oil, trans filter & fluid, and brake fluid. That I do know how to do.
Also I found that I have 12.48 volts measured from the negative battery post to the negative cable going to ground (not good). I get the same voltage measuring the same thing between the positive battery post and the positive terminal. I pulled each fuse and watched my volt meter but it never dropped so it much be somthing else. I have isloated the red main wire that is connected to this problem but have not figured out which wire it is.
I did change the engine oil, trans filter & fluid, and brake fluid. That I do know how to do.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Your VOM (voltmeter, ohmeter, milliameter) test meter must be set for CURRENT, not volts when you attempt to measure battery current drain. Many VOM's require you to plug one of your test probes into a separate jack on the front of the VOM in order to measure current.
One terminal on the TPS goes to 5 volts, one goes to ground, and the middle terminal is on the wiper arm and its voltage varies according to the throttle position. If you are measuring the terminal that goes to 5 volts, your voltmeter will always read 5 volts no matter what the position of the throttle.
One terminal on the TPS goes to 5 volts, one goes to ground, and the middle terminal is on the wiper arm and its voltage varies according to the throttle position. If you are measuring the terminal that goes to 5 volts, your voltmeter will always read 5 volts no matter what the position of the throttle.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by jtferris
I checked the voltage on my TPS with ignition on and also with engine running and it was 5.10 volts.
Originally Posted by jfb
There are some 8 wires on the jump start terminal and each of these wires has a fusible link
RACE ON!!!
