Cooking alternator and starter in 1HD-T (1 Viewer)

[Kfpals77]

Hi all,

I have an issue to solve.

I had already asked the same question in the 80 Series Tech forum but was advised to ask here.

During my 1FZ-FE (out) / 1HD-T (in) engine swap project I have been slowly going through the newly installed old electric system that fits the 1HD-T. During the installation, the 3 connector plug (IG, S, L) on the alternator back wasn't connected but only the main power cable. I didn't install the engine my self and didn't notice this until yesterday. When I finished connecting the alternator and measured the batteries while running, the voltage slowly increased up to 14 volts and I decided to do some tests with the lights etc. When I placed the voltmeter on the batteries with the lights on, the charging had stopped and the batteries were falling 12.5 volts and going down, rather fast. When I then switched off the truck the alternator was smoking. I decided to wait a bit, let it cool down, start again and measure after knocking the alternator with a hammer to see if the brush set / solenoids were stuck, but when I switched on the truck, it started immediately, with out me turning the key into the start position. The starter then didn't pull the bendix back into the starter - so I immediately turned of the car.

Therefore, now before having the smoking alternator repaired, I want to figure out why this happened. I find the behavior of the starter strange, it did start OK before connecting the 3 connector plug on the alternator (IG, S, L). I have been going through the electrical system, and finishing missing bits here and there (for example the voltage converter timer and relay weren't connected) and I thought I was going in the right direction, until yesterday after 5 minutes of extreme happiness and then what now seems to be an endless sadness...

Any thoughts on this? Could a faulty starter smoke the alternator? Or could a faulty relay or wiring smoke the alternator using the starter for the task?

 

[Kfpals77]

#2

I've been studying the electrical drawings too - hoping to gain better understanding of the system before I have the alternator repaired, hoping to find the issue before smoking the alternator again.

Is there someone here that could explain the purpose of the 24 Volt Hold Warning Relay to me?
It seems to be grounding the Alternator Terminal L.
Why?

 

[SHREDwagon]

#2

I've been studying the electrical drawings too - hoping to gain better understanding of the system before I have the alternator repaired, hoping to find the issue before smoking the alternator again.

Is there someone here that could explain the purpose of the 24 Volt Hold Warning Relay to me?
It seems to be grounding the Alternator Terminal L.
Why?

View attachment 2455312

I finished my swap last year so am fairly familiar with the EWD’s.
Are you running a 12V starter without the 24V switching relay? If so, the 24V hold relay operation is not applicable and hooking up the 24V relay would cause serious issues.
Ed: Given there’s numerous ways to wire a swap, whatever was connected to the alt when you got it should be left alone unless you want to study the EWD and rewire your fuse box.
Did your swap use an OEM starter relay?

 

[Kfpals77]

I finished my swap last year so am fairly familiar with the EWD’s.
Are you running a 12V starter without the 24V switching relay? If so, the 24V hold relay operation is not applicable and hooking up the 24V relay would cause serious issues.
Ed: Given there’s numerous ways to wire a swap, whatever was connected to the alt when you got it should be left alone unless you want to study the EWD and rewire your fuse box.
Did your swap use an OEM starter relay?

The starter is 24 volt. The alternator wasn't charging the batteries until I connected the 3 pin connector (IG, S, L) on the back side of it.
Not sure about the starter relay.

 

[SHREDwagon]

The starter is 24 volt. The alternator wasn't charging the batteries until I connected the 3 pin connector (IG, S, L) on the back side of it.
Not sure about the starter relay.

OK, so you kept 24V. Sorry, I can't be of much help. Hopefully someone else will chime in on relay function. GL.

 

[Dave 2000]

A couple of things. The starter contacts can stick together keeping the starter engaged. Check the earths are correct from the block to body and on to to earth.

I would check the changeover relay, there is the main one with the heavy cables and a smaller one that goes on the inner LH wing.

Other than that running an alternator without the cables connected can fry it internally.

Not much help as I purchased the 80 already diesel, although it was soon swapped to 12v start.

regards

Dave