Thread: 4BD1 70A ALTERNATOR

Brian,

If you are driving daylight only you can disconnect the alternator by unplugging the multi plug to it, the engine reqs no power really, and brake lamps etc will be fine with an already fully charged battery. If you leave it connected etc, you COULD blow some headlamp globes, over load blower motor and A/C fan motor, boil battery, etc etc.

JC

(PS, 'box going in this week)

Thanks Justin, Yeah thats probably the safest way. Once its started there,s very little power needed, only for indicators and brakes, probably go that way. Thanks.....brian

If you can keep the voltage below 14.5 I would drive it. I've done it before when my reg wasn't set correctly. You can try and adjust it but if it was working correctly then suddenly went crazy it sounds like it's buggered. Check the wire that the reg references the ALT voltage(yellow wire on the reg side of the plug ,if it's got any resistance the reference voltage will be low and the reg will compensate by increasing the ALT output voltage. Also check the white wire (B+) for the same volts as the ALT output. The black wire is earth; this could also cause issues if there is a bad connection.
If you drive for a long time with high voltage the battery will suffer

I have to go out now.

Electricals are not my area, but i have Isuzu 4BD1T manuals with info and tests for that alternator.

If you don't have these or are not sorted when I return I will try and put some relevant info up here.

Edit: Manual pages in pdf format, zipped attached.

I once paid an auto electrician to fit an alternator. It ran at close to 16v for a couple of months before I noticed. I didn't blow any bulbs and one of the batteries I was running then has just died around it's 6th birthday. I pulled them out after 5 years.
I kept telling him the signals don't match the wiring diagram, he kept telling me the diagrams are never wrong.

I rewired it myself, now it's a steady 14.2V. This is an OEX alternator, copy of the hitachi allegedly.

My voltage reg on the IIA packed it in recently. 11V or so at idle up to 17V or so. I probably drove it for 3 weeks or so without realising. Battery etc seem fine.

Today I got around to replacing the regulator in my alternator. Luckily I bought a set of replacement brushes as well as they were just about worn out. Anyhow after fitting the new regulator and brushes it is still doing the same thing - light on and high voltage, anyone got any ideas????

bad earth or sense line