Disconnecting Battery Starts Car

[Connie]

Good morning to you all, on this wonderful forum. This is Connie's husband Bob. I have an '03 GT. Recently at times it will not start. It will CRANK strong, but that's it. I bought it new in 2003, so there are no surprises I have to worry about. I do have a Diablo Progammer, but I installed it 14 years ago. The past month or so, it wouldn't start at times. Thank goodness it was in the garage each time. Since I didn't know why it wouldn't start, I decided to disconnect the Negative Terminal, as a hail mary, and she CRANKS RIGHT UP!! And the intervals are getting shorter between each reset. Is there a logical reason for this issue?

 

[ttocs]

connect the battery and then test the voltage with out starting it. After letting it sit over night or a couple of days check the voltage again and see what it says. It sounds like there is a parasitic draw on the electrical system that is draining the battery. IF I had to guess I would start at the mach amps, or start looking even if you do not think you have them. Its very common to bypass them but leave the one in the dash and they have been known to have this problem for a while

 

[01yellercobra]

How old is the battery?

 

[Connie]

Thank you ttocs, for such a quick response! I should've brought out that I haven't had the MACH System for over 6 years. I have a aftermarket JVC CD Head Unit with Alpine Speakers and Sub, and separate Alpine amps for both. But, the strange thing is, it will CRANK like crazy, like it has plenty of voltage, but will not start at times, until I disconnect and reconnect the battery. What's funny about this whole problem is, it only happens at home. There are no issues when we go anywhere after I do the Disconnect and Reconnect of the Battery. It boggles my mind. But, I'll check the voltage anyway. Thank you again, Bob

 

[Connie]

How old is the battery?

Hello there 01yellercobra. The battery is almost 5 years old. With 17,000 on it since I installed it. But, the thing is, it CRANKS like crazy, like there is plenty of voltage and will not start sometimes, until I disconnect and reconnect the Battery. Your right, the Battery is getting older, but it cranks the engine fine, but will not start at times. It's just too weird.

 

[Silver95bird]

what is the fuel pressure like?

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[Connie]

what is the fuel pressure like?

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Hi Silver95bird. That I haven't checked, but was wondering about. I don't know how to go about checking the fuel pressure, but it still a mystery, why my car starts, AFTER I disconnect and Reconnect the Battery.

 

[Connie]

Thank you ttocs, for such a quick response! I should've brought out that I haven't had the MACH System for over 6 years. I have a aftermarket JVC CD Head Unit with Alpine Speakers and Sub, and separate Alpine amps for both. But, the strange thing is, it will CRANK like crazy, like it has plenty of voltage, but will not start at times, until I disconnect and reconnect the battery. What's funny about this whole problem is, it only happens at home. There are no issues when we go anywhere after I do the Disconnect and Reconnect of the Battery. It boggles my mind. But, I'll check the voltage anyway. Thank you again, Bob

Hi again. I just checked the voltage after Connie got home from shopping, only two miles from home. After that short trip, the battery tests at 12.55 Volts. Seems like plenty of voltage. I'll check it again tomorrow as you said. And, I'll listen for the Fuel Pump to come on also, when I turn the key, and see if I hear it make a sound. Maybe it's an intermittent Fuel Pump problem. But still, why does it start after the battery disconnect, reconnect? Puzzles me.

 

[01yellercobra]

Its not just the voltage. Sometimes a battery has enough power to spin the engine, but not enough to also power the pump, ignition, sensors, etc. If the voltage is still showing ok I would have it load tested. Maybe there's a cell on its way out and disconnecting and reconnecting the battery resets it somehow.

 

[ttocs]

so you did have the mach system? More then likely the amp in the dash is still connected.

 

[Connie]

Its not just the voltage. Sometimes a battery has enough power to spin the engine, but not enough to also power the pump, ignition, sensors, etc. If the voltage is still showing ok I would have it load tested. Maybe there's a cell on its way out and disconnecting and reconnecting the battery resets it somehow.

You know...that does make sense. I've never had a battery last 5 years. Maybe as you said, I'm resetting something by disconnecting then reconnecting the battery. Thank you. I should look into getting a new battery anyway.

 

[Connie]

so you did have the mach system? More then likely the amp in the dash is still connected.

Thank you for your input. Being over 6 years ago, do you believe the Mach Amp in the Dash could start problems after that long?

 

[ttocs]

Thank you for your input. Being over 6 years ago, do you believe the Mach Amp in the Dash could start problems after that long?

I use to promote wiring into them and keeping them but for the past 10 yrs they have just been known to become a drain. To find the drain you need to disconnect the battery and set your multimeter to amperage/current and insert it between the disconnected lead and the battery. Take a look at the reading and then you start puling fuses one at a time till you see the current draw drop. At the point it does you have the circuit narrowed down and its easier to figure out what on that circuit is creating the draw.

Or look down below the radio and disconnect the harness that goes to the silver box with all the holes in it. If the amp was wired into then you will loose sound from the speakers, we can fix that later if we first narrow down that the amp is the draw.

 

[07GtS197]

Have you checked for codes? I wouldn’t rule out pats or a flaky crank sensor.


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[Connie]

I use to promote wiring into them and keeping them but for the past 10 yrs they have just been known to become a drain. To find the drain you need to disconnect the battery and set your multimeter to amperage/current and insert it between the disconnected lead and the battery. Take a look at the reading and then you start puling fuses one at a time till you see the current draw drop. At the point it does you have the circuit narrowed down and its easier to figure out what on that circuit is creating the draw.

Or look down below the radio and disconnect the harness that goes to the silver box with all the holes in it. If the amp was wired into then you will loose sound from the speakers, we can fix that later if we first narrow down that the amp is the draw.

I go and check the MACH Amp.

 

[Connie]

Have you checked for codes? I wouldn’t rule out pats or a flaky crank sensor.


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Good morning. I was thinking about getting out the Diablo Programmer, and check for codes. Thank you.

 

[96blak54]

I see
'03 GT
Diablo Tuner.

03 gt means returnless fuel and has a fuel pressure switch on the fuel rail known to be faulty, send false signals, or just simply not work.

But since you have found consistency removing the neg terminal as a reset and improves start up, tells me the computer over rides the diablo programming untill the computer figures out whats.

I would reset the computer. Take the program back to stock. Just to rule out a possible problem with the tune.

 

[01yellercobra]

I see
'03 GT
Diablo Tuner.

03 gt means returnless fuel and has a fuel pressure switch on the fuel rail known to be faulty, send false signals, or just simply not work.

But since you have found consistency removing the neg terminal as a reset and improves start up, tells me the computer over rides the diablo programming untill the computer figures out whats.

I would reset the computer. Take the program back to stock. Just to rule out a possible problem with the tune.

Eh. A tune that was installed 14 years ago doesn't suddenly go bad. They usually only corrupt when transferring between places. Such as computer to handheld or handheld to car. The stock programming is gone. Theres no stock info to override the Diablo tune. It doesn't work that way. Otherwise everyone that has modified cars would have issues when swapping batteries.

FRPS is a possibility, but generally they either throw a code or just die completely. I had one in our 06 throw a code. The two I've replaced between my 01 and 04 blew the diaphragms. And there was no way disconnecting the battery would fix that.

 

[Connie]

I see
'03 GT
Diablo Tuner.

03 gt means returnless fuel and has a fuel pressure switch on the fuel rail known to be faulty, send false signals, or just simply not work.

But since you have found consistency removing the neg terminal as a reset and improves start up, tells me the computer over rides the diablo programming untill the computer figures out whats.

I would reset the computer. Take the program back to stock. Just to rule out a possible problem with the tune.

I thank you for your input on. I've been sick, hoping to get better and understand this. It's really hard, when you buy a car brand new 17 years ago, and not a single issue in all these years. Having no track record of problems to go by. I'm grateful it's been sooo reliable. These SN95'S are a sturdy bunch.

 

[Connie]

Eh. A tune that was installed 14 years ago doesn't suddenly go bad. They usually only corrupt when transferring between places. Such as computer to handheld or handheld to car. The stock programming is gone. Theres no stock info to override the Diablo tune. It doesn't work that way. Otherwise everyone that has modified cars would have issues when swapping batteries.

FRPS is a possibility, but generally they either throw a code or just die completely. I had one in our 06 throw a code. The two I've replaced between my 01 and 04 blew the diaphragms. And there was no way disconnecting the battery would fix that.

I think your correct on the TUNE. Once you reprogram a computer, all it does is do what it's told, unless it completely goes down and doesn't function at all. I'm still thinking along your theory that the Battery could be the issue. Batteries are a very sensitive part of vehicles these days. Kind of like fuel systems as we all know. The battery is 5 years old. Once I feel better, I'll get into it. I plugged in the Diablo to get a code, but I guess since I did the battery disconnect, and reconnect, no codes come up. Working great now. I'll have wait and hook it up next time it cranks and doesn't start. Thank you again for the help.