PAGING ALAN!! Need insight. Chassis Positive??
05-12-2011, 12:03 AM
#16
Rennlist Member
Thread Starter
Thanks Stan,
As you suggest, these appear to be the next stop(s) on the tour.
As for what I'm measuring and why, I accidentally discovered that the chassis (actually the exhaust tips) were positively charged, and being curious, I took the digital Volt meter, set to measure DC volts, and discovered to my dismay that the battery negative post to the exhaust tips were showing 12.89 volts. Not a good thing.
Battery hold-down is in place and secured.
,
As for what I'm measuring and why, I accidentally discovered that the chassis (actually the exhaust tips) were positively charged, and being curious, I took the digital Volt meter, set to measure DC volts, and discovered to my dismay that the battery negative post to the exhaust tips were showing 12.89 volts. Not a good thing.
Battery hold-down is in place and secured.
,
I am not really sure what your measuring and why, what is the meter set to measure?
is there a battery hold down installed?
on a long shot check that the wire harness hasnt worn through on the front swaybar and that the starter connections are not touching the oilpan.
also check the positive cable along it whole route from the bat box to starter and also the ABS connection and or see if it is shorting near the ABS /power steering reservoir
is there a battery hold down installed?
on a long shot check that the wire harness hasnt worn through on the front swaybar and that the starter connections are not touching the oilpan.
also check the positive cable along it whole route from the bat box to starter and also the ABS connection and or see if it is shorting near the ABS /power steering reservoir
05-12-2011, 12:05 AM
#17
Rennlist Member
Thread Starter
05-12-2011, 12:09 AM
#18
Rennlist Member
Thread Starter
Dan,
Agree.
It's where to start looking, and the complexity of the system that's kind of freaking me out right now.
Also, the fact that there has been no evident signs of a complete dead short yet.....other than my "oh ****" moment.....
It's where to start looking, and the complexity of the system that's kind of freaking me out right now.
Also, the fact that there has been no evident signs of a complete dead short yet.....other than my "oh ****" moment.....
475hp/460lb.ft
05-12-2011, 12:14 AM
#20
Rennlist Member
Thread Starter
Neil,
I'll try the OHM readings as soon as I get back to it, but right now, the positive charge is actually reading slightly higher from the battery negative terminal to the exhaust tips than from the battery negative terminal to the battery positive terminal.
Hence the page for Alan to help out.
Hence the page for Alan to help out.
With the ground strap in place and the +ve connector disconnected!
Put your meter on its lowest OHM range and measure from the exhaust to the grounding point under the back panel ( next to the wiper motor) and then from exhaust to the -ve terminal on the battery.
All should read either zero or close to.
Remember, the exhaust is supported in rubber straps, so if the ground at the engine end is broken you could get strange results - i'm guessing the current in that 12v you see is so low it does not make a problem.
Put your meter on its lowest OHM range and measure from the exhaust to the grounding point under the back panel ( next to the wiper motor) and then from exhaust to the -ve terminal on the battery.
All should read either zero or close to.
Remember, the exhaust is supported in rubber straps, so if the ground at the engine end is broken you could get strange results - i'm guessing the current in that 12v you see is so low it does not make a problem.
05-12-2011, 07:44 AM
#23
Captain Obvious
Super User
Super User
05-12-2011, 09:49 AM
#25
Rennlist Member
Thread Starter
Fair Enough but
a) I was thinking more of the big picture when I made that comment....i.e. how and where are they run through the car; what are the most probable locations for the short; and the implications for damage to the rest of the electronics as a result of the incident.
b). I'm not much of a vehicle electrics guy, so this sort of thing I'm generally not good with.
c). The point that has me particularly baffled is "how could this happen without evident heat/smoke/pyrotechnics?" I would expect that the arc welding that would be anticipated would be obvious even to me.
b). I'm not much of a vehicle electrics guy, so this sort of thing I'm generally not good with.
c). The point that has me particularly baffled is "how could this happen without evident heat/smoke/pyrotechnics?" I would expect that the arc welding that would be anticipated would be obvious even to me.
05-12-2011, 09:53 AM
#26
Rennlist Member
Thread Starter
Malcolm,
Thanks,
The battery will be coming out as a first priority when I get back to it tonight.
Any direction on what setting/readings to look for on the DVM would be appreciated too!
The battery will be coming out as a first priority when I get back to it tonight.
Any direction on what setting/readings to look for on the DVM would be appreciated too!
05-12-2011, 09:58 AM
#27
Rennlist Member
Thread Starter
Dave,
I'm beyond saying that 'that's not possible' when it comes to these cars, however, I have to agree with Imre on this one.
Can you explain a bit please?
Can you explain a bit please?
05-12-2011, 10:00 AM
#28
Rennlist Member
Thread Starter
Checked and Double-checked.
05-12-2011, 11:39 AM
#30
Rennlist Member
"Originally Posted by SharkSkin
If the battery ground strap is disconnected then the voltage potential between '-' and the exhaust makes perfect sense..."
Yes it does - The meter is acting as a very high resistance load between -ve and the exhaust ( ground) - switch the meter up to a higher voltage range and the reading should be less.
This may sound like a dumb question - but with the battery totally disconnected, do you still see the 12v on the exhaust to the ground strap, or from the disconnected +ve cable to chassis or exhaust??
If the battery ground strap is disconnected then the voltage potential between '-' and the exhaust makes perfect sense..."
Yes it does - The meter is acting as a very high resistance load between -ve and the exhaust ( ground) - switch the meter up to a higher voltage range and the reading should be less.
This may sound like a dumb question - but with the battery totally disconnected, do you still see the 12v on the exhaust to the ground strap, or from the disconnected +ve cable to chassis or exhaust??