Have a Battery draw... - Impala Tech
Electrical & Wiring Troubleshooting electrical problems

 
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post #1 of 8 (permalink) Old 10-29-2019, 09:58 PM Thread Starter
 
 
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Have a Battery draw...

I recently bought a 65 Impala and it was LS swapped with a 2008 5.3 and a 4L60E. It has a Sniper EFI mounted as the builder wanted to make the 5.3 look as much like a SBC as he could. For the transmission, he ran an EZ-TCU.

I bought the 65 sight unseen and had it shipped to me.

The battery was dead coming off the trailer and I found that the battery would continue to die.

He mounted the EZ-TCU on the fender well beside the battery so I noticed the blue light on the brain would blink even when the key was in the off position. The 12v switch from the sniper and EZ-TCU are both ran to the fuse box and I checked it with a multi-meter. It read as a good key on switch.

The TCU and the sniper still draw power and blink and light up with the key in the off position. This results is a 2.75 parasitic draw on my battery, killing it daily. I’ve resorted to unhooking my negative cable everyday.

A third player is the MSD ignition that’s also spliced off the same port in the fuse box as the EFI and the TCU and into a relay.

The think maybe the relay (for the MSD LS ignition) is the issue. The 30 connection on the relay is ran to another ignition port on the fuse box.

Any experience with similar problems or suggestions?
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post #2 of 8 (permalink) Old 10-30-2019, 12:44 AM
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I do not know if those aftermarket products all require power to retain their programmed settings or not (I know the MSD ignition box doesn't it can be turned off without ill affect and yes it draws a lot of power). I had a TCI TCU for my 4L80e and it was happy with the power off, but the Holley Sniper I have never seen. If Holley says it can live with out power an easy solution and a possible deterrent to auto theft is a battery disconnect at the battery post or some where else in the car (NHRA rules says it has to be on the back of the car and labeled as to how to turn it off such as push to start or labeled on off it rotates).

Simple and relatively cheap.

Big Dave
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post #3 of 8 (permalink) Old 10-30-2019, 08:34 AM Thread Starter
 
 
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Quote:
Originally Posted by Big Dave View Post
I do not know if those aftermarket products all require power to retain their programmed settings or not (I know the MSD ignition box doesn't it can be turned off without ill affect and yes it draws a lot of power). I had a TCI TCU for my 4L80e and it was happy with the power off, but the Holley Sniper I have never seen. If Holley says it can live with out power an easy solution and a possible deterrent to auto theft is a battery disconnect at the battery post or some where else in the car (NHRA rules says it has to be on the back of the car and labeled as to how to turn it off such as push to start or labeled on off it rotates).

Simple and relatively cheap.

Big Dave
That is what I do at the moment. However, I hate that everywhere I drive, I have to pop the hood, disconnect the battery and then reconnect before I leave. It bothers me that it’s not connected correctly.
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post #4 of 8 (permalink) Old 10-30-2019, 03:02 PM
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What I am talking about is a big honking switch (big as in the amount of current it can conduct not size wise). You have to raise the hood, yes: but after that it is flipping a lever to tun on or off the switch.

https://www.amazon.com/Universal-Dis...a-601662578568

or this type that goes in the back of the car for racing 9usually requires a rear trunk mount battery).:

https://www.amazon.com/dp/B07MPW8XQ4...NsaWNrPXRydWU=

Big Dave
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post #5 of 8 (permalink) Old 10-30-2019, 05:37 PM
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The Sniper EFI should have two leads - positive and negative - going directly to the battery, no exceptions! There will also be a pink lead that should have its own keyed ignition source. Sharing this with your MSD is asking for gremlins. I'm not sure if this solves your particular issue, but it will help narrow down and eliminate a few possible problems.

1968 Impala SS
496 Stroker
T56 Conversion
3.73 Posi-Trac
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post #6 of 8 (permalink) Old 10-30-2019, 06:47 PM
BA.
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Quote:
Originally Posted by 68WASAGOODYEAR View Post
The Sniper EFI should have two leads - positive and negative - going directly to the battery, no exceptions! There will also be a pink lead that should have its own keyed ignition source. Sharing this with your MSD is asking for gremlins. I'm not sure if this solves your particular issue, but it will help narrow down and eliminate a few possible problems.

I'm with 68WAGY

I don't have any directly relatable experience with that combo but my gut was telling me the same thing. I was surprised to hear the way that the MSD was wired in there. Sounded like a way for power to 'leak' to the EFI in an unwanted way.

HOW A NOVICE REBUILDS A 66 IMPALA CONVERTIBLE:
http://www.impalas.net/forums/blog.php?u=1432
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post #7 of 8 (permalink) Old 10-30-2019, 08:45 PM
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Quote:
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Quote:
Originally Posted by 68WASAGOODYEAR View Post
The Sniper EFI should have two leads - positive and negative - going directly to the battery, no exceptions! There will also be a pink lead that should have its own keyed ignition source. Sharing this with your MSD is asking for gremlins. I'm not sure if this solves your particular issue, but it will help narrow down and eliminate a few possible problems.

I'm with 68WAGY

I don't have any directly relatable experience with that combo but my gut was telling me the same thing. I was surprised to hear the way that the MSD was wired in there. Sounded like a way for power to 'leak' to the EFI in an unwanted way. <img src="http://www.impalas.net/forums/images/smilies/confused.gif" border="0" alt="" title="Confused" class="inlineimg" />
"Sharing" the Snipers keyed ignition source with another accessory is a good way to get a no-run condition where the ECU goes unresponsive. Ask me how I know!

1968 Impala SS
496 Stroker
T56 Conversion
3.73 Posi-Trac
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post #8 of 8 (permalink) Old 10-30-2019, 10:14 PM
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Transistors are intolerant to any variation in voltage, or change in voltage polarity. This is why all transistors in the car will die a fiery death if the car is improperly jumped (get the cables on wrong), or you try and jump a really dead battery off with a whimpy cable that can not support the 200 plus amps of current.

Your ECU is wired directly to the battery not because it needs a lot of power to run but because it uses the battery like a shock absorber to flatten out any voltage spikes coming off your alternator on an older car with the unregulated voltage control found in am older AC-Delco 10SI style alternator. You need the rock steady voltage out put by a newer AC-Delco CS-130D alternator (the 1986='97 one wire style alternator). If you don't have one now replace your old alternator with the CS or newer models.

Big Dave
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