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help please - electrical problems after NA to TT swap


GTR Fever

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Hello again,

 

Been experiencing some electrical problems after I swapped from NA to TT (Aristo engine) with auto tranny. These problems include:

 

1. Battery dies when car is parked - I don't drive the Supra very often due to my work obligations but she is started at least once a week. However, after 2 to 3 weeks, the battery dies. I've checked the charging rate on the alternator and it's good but something drains the battery.

 

Also, if I remove the battery terminal and put it back on, it sparks as if something is staying on.

 

 

2. A/C step-up simply does not work. Meaning that when the A/C compressor is engaged, the RPM drops resulting in the compressor switching off. Immediately after the compressor switches off, the RPM raises again allowing the compressor to be engaged then the RPM drops again repeating the whole story. The end result is the compressor switching on and off constantly on idle.

 

Any advice on these items? And can I fix them myself or do I have to carry the car in by a technician?

 

Thanking you in advance guys and gals.

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Could be the battery needs replacing.

Battery drain could be caused by the alarm/stereo system.

Check all the earth points and battery terminals are clean and secure.

Check condition/tension of the V belt.

Sparking when fitting the battery terminal is normal.

 

http://www.turbosupras.com/pdfs/JZA80%20TSRM/CH.pdf

Edited by Nic (see edit history)
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Seems like the ECU isn't getting the aircon message so isn't idling up. Possibly missed a wire somewhere...?

 

I would suspect the battery - try leaving it disconnected and then check voltage with a multimeter after a day or two. Could also be an idea to bench charge it and then drop test.

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The battery terminal sparking is completely normal. It's just all of the devices in the car charging up to 12V simultaneously. The current should drop to next to nothing within a second or two.

 

If you have a multimeter it's pretty easy to isolate a drain on the battery. You can do it one of two ways. The (slightly) harder way is to set the multimeter to read current and then place it in line with one of the battery terminals. The easier way is to set the multimeter to read voltage and then connect it across your battery.

 

Whichever way you choose, record what the current or voltage reading is when the engine is turned off and the car is locked. (You may need to tape down the bonnet switch on your alarm if it has one, to fool it into thinking the bonnet is down) Then, one by one, remove and replace each of the fuses in the fuse box. For each fuse, record by how much the current drops or the voltage increases. When you have gone through all of the fuses, you should see one that has a much bigger difference than the rest. This is the circuit to concentrate on. There are plenty of wiring diagrams online to help.

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^ +1

 

my battery terminal sparks when put on,

 

 

also if i leave my car around 2 weeks the battery isnt the best. asume either old, or alarm drains it (or both) so i can live with that.

 

if i were you id just disconnect the air con, unless you NEED it

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