85 gts w/ 7mgte swap not charging battery

[Yodarolla86]

I bought the car like this from a friend. It's been through many owners with a myriad of wiring hack jobs but runs well. My main problem is the charging system, as it will not charge the battery. Im still using the corolla fuse box. With the 7.5amp(charge) fuse in the light on the cluster stays on, with it out the light turns off. On the Alt side I had to replace about 5" of wiring from the 2 white wires due to corrosion. They were ran under the rad support to driver side and cheap soldered to the battery power cables that ran from the starter to the battery which was relocated to the trunk. I had to replace the starter side cable with a 1awg because the stock 6awg was still being used to compensate the 8ft length. I then powered them all to a power distribution block mounted to where the battery originally was. Any help would be appreciated.

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[Yodarolla86]

I bought the car like this from a friend. It's been through many owners with a myriad of wiring hack jobs but runs well. My main problem is the charging system, as it will not charge the battery. Im still using the corolla fuse box. With the 7.5amp(charge) fuse in the light on the cluster stays on, with it out the light turns off. On the Alt side I had to replace about 5" of wiring from the 2 white wires due to corrosion. They were ran under the rad support to driver side and cheap soldered to the battery power cables that ran from the starter to the battery which was relocated to the trunk. I had to replace the starter side cable with a 1awg because the stock 6awg was still being used to compensate the 8ft length. I then powered them all to a power distribution block mounted to where the battery originally was. Any help would be appreciated.

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This is how it looks now.

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[Yodarolla86]

Is this forum dead

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[JDM AE86]

Id start from tge alt and work your way back. Check the alt and make sure it is putting out what it should be and then make sure the voltage is the same at every connection all the way down to the batt.

[Yodarolla86]

Alt is new but ok I'll check the voltage

[Yodarolla86]

Idk we checked everything. Is it possible I need the fuse box from the 7mgte. The fusable links are different

[dr.occa]

Idk we checked everything. Is it possible I need the fuse box from the 7mgte. The fusable links are different

The 7MGTE has a different load requirement than that of the 4AG/C. It's electrical load demands are bigger and its alternator will be putting out what the 7MGTE needs which is more than what the AE86 harness is equipped to accommodate.

*edit: reading my above response - what I said was retarded. Your factory (or the Supra harness) will pull what it needs for factory needs and not any more unless you over load a circuit(s) with more draw than ea circuit(s) is wired for.

Anyway...sorry 'bout that. I wasn't thinking obviously.

[Yodarolla86]

Idk we checked everything. Is it possible I need the fuse box from the 7mgte. The fusable links are different

The 7MGTE has a different load requirement than that of the 4AG/C. It's electrical load demands are bigger and its alternator will be putting out what the 7MGTE needs which is more than what the AE86 harness is equipped to accommodate.

I'm using the 7mgte harness. Battery is relocated to the trunk. I just need to know ow which wire from the alt is used to charge the battery so I can make a fusable link

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[dr.occa]

Toyota-Hi-Spd-Alt-Terminals.jpg (39.7 KiB) Viewed 6341 times

"B" is your charging circuit @Yodarolla86.

[Yodarolla86]

Alt was relocated to passenger side under the intake. There are 2 10guage white wires from the positive post down to a positive distribution block where the battery used to be. Should I run them straight to the battery? When checking voltage I'm getting 11.6-12 all across every connection but it drops very slowly. I brought the battery to the front temporarily to see if the rear location had a voltage drop due to the 0 guage cable.

[JDM AE86]

With it running put a meter on the(B) post on the alt. It shouldn't be any lower than 13v running.

[Yodarolla86]

Getting 11.9 volts

[JDM AE86]

Probably need a new alt. It isnt charging. With engine running pull a battery cable off and it should stay running if the alt is good.

[gzus13]

You should also check the "IG" terminal on the alternator. If that is not getting +12V switched power, the coils in the alternator won't energize and it cannot generate any power.

Here is a good overview of alternators: http://www.pirate4x4.com/tech/billavista/Wiring/Part2/

Hope it helps,
Chris