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Mar 14, 2018, 01:33 AM
Chino Renegade oh-gee, yo
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Datsun 510

by Thomas Walter

For those 510s with the simple T style connector into the back of the alternator, this is a pretty straight forward conversion.

The Alternators
The OLD (externally regulated Alternator) had the N and F connected by the plastic T connector.

N Neutral was connected by a Y (yellow) wire.
[This is the top of the T connector]
F Field was connected by a W/B (White, black stripe) wire.
[This is the stem of the T connector]
The NEW IR ALT (internal regulated alternator) will have two connections, also in a T configuration like the old unit.

S Sense is connected to the battery (direct +12 Volts)
[This is the top of the T connector]
L Lamp is connected to the Warning lamp light.
This connection has TWO functions. By Sensing the circuit is turned on when the ignition is, it will energize the alternator. SECOND: when the alternator FAILS, and the engine is running, it will GROUND this connection providing a ground path to turn on the ALT warning lamp. (you should see the ALT lamp glow when the ignition is first turned on, before starting the car).
How to modify the wiring
Before tossing that old voltage regulator into the trash bin
cut OFF the connector block.

Splice the W (white) wire to the Y one. (Sense circuit)
Splice the W/R (white/red) wire to the W/B one. (Lamp circuit)

This the wiring at the HARNESS, compare it to the regulator wiring, both should be the same but some replacement units did not follow the color code. See Kelvins wiring diagram to be sure.

Plug the connector back onto the wiring harness. Quick, simple, painless to swap back if the need every arises.

Things to consider
The Alternator lead to the battery may be too small to handle the additional current capability of the new alternator. (Best to use a FUSED 10 gauge wire direct from the alternator to Battery).

There is also a splice in the harness, of the alternators positive lead (white with a red stripe) and the main power line from the starter to the fusebox (white). You may want check the condition of the splice, as it is buried in the harness and, if corroded, could cause problems. [From Robert Broad]

For those 72 and later 510s that use the electrical choke. The choke relay was powered up by the voltage that appeared on the N terminal of the relay. To energize correctly, the relay was designed for the lower voltage (about 6 volts) of the N Terminal when the engine was running. Even if you replaced the Carburetor, the relay most likely still wired up, so you may see the ALT light glow for this extra load).

Alternator Mounting Brackets
Most of the IR Alternators will have 10mm holes, so use a bracket from a later series L engine to bolt up the alternator (the 510s OEM 8mm bolts had a habit of breaking).

Quick, simple, and clean installation. Also this allows for a quick return to a stock setup should you ever desire to do so.

Honda Civic D15B7 idle issue fixes-------------
Bad Idle Troubleshooting

This is for high and roaming idles but may work for low idles as well.

First, terms:

TB Throttle Body
IM - Intake Manifold
IACV Idle Air Control Valve (also called the Electronic Air Control Valve or EACV)
FITV Fast Idle Thermo Valve
TPS Throttle Position Sensor

The idle on our Hondas is a tricky thing. It is controlled by two main sensors: the FITV and the IACV. The FITV is a mechanical valve that is controlled by coolant temperature (there is no ECU plug to it). When the coolant is cold the valve is open and letting air into the IM through a hole in the TB before the throttle plate. This essentially creates a small vacuum leak which in turn lets the motor idle higher than normal (supposed to be around 1500-2k for warming up). As the coolant warms up the valve closes and no longer lets air in through the hole in the throttle body. All the while the IACV, which is ECU controlled, is letting small amounts of air into the IM through another hole in the TB. Any amount of extra air the ECU is not expecting will confuse it and you will get either a high idle or a roaming/hunting/fluctuating idle. On to the troubleshooting.

First things first, dont skip any of these steps. From what I have read (and experienced) usually small dumb things cause these problems so dont overlook anything. Also refer back up to the pictures if need be.

1) Check your vacuum routing. On the underside of your hood there should be a vacuum diagram. If there isnt a diagram under there, there is one in a Helms, Chiltons, or Haynes manual for your car (you should have one of these anyway). Remember, ANY extra air will confuse the ECU. Check for cracked or bad vacuum hoses. If in doubt just replace the hose, they are cheap.

The PCV valve could also be the culprit. Take it out and examine it. If it is cracked it could be causing a vacuum leak. Replace the peice if you arent completely sure it is ok (the helms/chiltons/haynes manuals tell you how to check it).

2) Check to see that your throttle plate is closed all the way. Take your intake off at the TB and check to see that nothing is blocking the plate. If nothing is in the way and it isnt closed all the way, loosen your throttle cable.

3) Check to see if the nuts holding the TB and the IM on are tight, this was the source of my idle problem. If they are loose, tighten them.

4) Bleed your coolant. Some air bubbles may throw the FITV off and keep the valve open.

5) Take the 3 10mm bolts out of the FITV (you dont have to take off the coolant lines). Then take off the 2 8mm bolts off the plate on the back of the FITV. Once the plate is off you will see a white plastic thing, screw that all the way in. This causes a TON of peoples hunting idle problems (its a source of a vacuum leak). Put the FITV back on and start the car up. If it still idles bad go on.

6) Clean the IACV screen(s). See Ozs write up elsewhere on G2IC.

7) Make sure your car is completely warmed up. With it running, take the intake off the TB. There are 2 holes right in front of the throttle plate, these are the holes that feed the IACV (top hole) and the FITV (bottom hole). With your finger, cover up the bottom hole (it should NOT be sucking if your car is warmed up). If the idle goes down the FITV is to blame, either get a new one or take it apart and screw the valve completely closed (I have only read of people doing this, so I dont know exactly how. Also, you will have to keep the engine speed up yourself when the car is cold).

Next cover both holes up with your fingers. The car should sputter and die (or almost die). If it does then the source of your crappy idle is the IACV. Replace it. If you want you can test the IACV. Shut the car off and put + battery voltage to the blk/yel terminal (on the valve) and momentarily touch ground to the blu/yel side. When doing this the valve should click, if it doesnt, replace it.

If, when covering both holes the car still has a high idle, you have a vacuum leak somewhere. Again check the IM and TB nuts. You can spray carb cleaner around those areas and if any gets sucked in (the engine will rev) you have found your leak. Another source of vacuum leaks are where the FITV and IACV connect to the IM. Either replace the gaskets or use silicone gasket sealant.

If nothing has worked you should test your TPS. Probe the middle wire on the TPS plug (with the key on but not running, and the plug still connected to the sensor) with the + probe on the volt meter, and the neg probe to ground. You should have .5v with a fully closed throttle plate and 4.8v with it wide open. If the TPS is off, replace it. My TPS was .425v to 4.55v and it idles fine now so I dont know how big the margin of error is. Also, it is pretty rare for these to go bad.

9) If, still, nothing has worked you might want to try a new ECU. This also is very unlikely, but worth a try.

10) If it still idles bad, go through the steps again.

I really really hope this helps someone out. It was a pain to have this mysterious problem and very little info on how to go about troubleshooting it. Comments or suggestions are welcome.
Last edited by Wrench66; Oct 25, 2018 at 01:50 AM.
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Mar 21, 2018, 09:44 PM
Chino Renegade oh-gee, yo
Wrench66's Avatar
Thread OP

Futaba T6XA Super

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