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I put a 96-00 Alternator into my '49 Buick StreetRod build because I needed a CCW alternator. I ran the engine for the first time yesterday... the brand new alternator ran solid at 14.5 volts for a few minutes then fluctuated as high as 18v,,, then died. I had only the "B+" and "I" terminals wired. My Tech question is, can the 96-00 or even the 92-95 Alternator be used without the ECM? Did I kill the alternator or was it a defect?
Isn't one of the wires responsible for adjusting the output voltage of the alternator based on the load on the electrical system (ELD)? Is this a US model alternator?
Isn't one of the wires responsible for adjusting the output voltage of the alternator based on the load on the electrical system (ELD)? Is this a US model alternator?
I've read conflicting statements regarding the other wires... that is why I am here to see if anyone with actual Honda Alternator knowledge can answer my question.
I don't know if it is a US... bought it from DB Electrical and their tech help is non-existent... the only dept answering the phone is their sales.
I'm not sure if the ecu connection is required, but hopefully someone with more insight can chime in.
Based on that thread, a 4-pin is US... so yes, mine is a US.
According to redtherocket in Reply #3 in that thread... I interpret that as the other 3 pins don't need to be wired for Alternator to function.
The image with the connector and note regarding "Must have a 1K resistor between the FR and IG terminals" was interesting. Normally, when running, the ECU sends a 5V reference voltage through the FR circuit to the voltage regulator. Seems like that set-up would be to drop the voltage via the 1K resistor from the IG (~ 12 volt battery power with ignition ON) to the FR terminal.
The image with the connector and note regarding "Must have a 1K resistor between the FR and IG terminals" was interesting. Normally, when running, the ECU sends a 5V reference voltage through the FR circuit to the voltage regulator. Seems like that set-up would be to drop the voltage via the 1K resistor from the IG (~ 12 volt battery power with ignition ON) to the FR terminal.
When the alternator started to fluctuate, I tapped the FR wire to B+ and it arced like it was a ground. I'll pick up a 1k resistor as soon as I find a "used" alternator locally. I went with the Honda alternator for reliability...I didn't realize the cheapest replacement would be a $180 rebuild from the local parts stores.
When the alternator started to fluctuate, I tapped the FR wire to B+ and it arced like it was a ground.
The alternator FR pin behaves like a variable ground. However, the FR circuit is only rated for 5V. When you applied 14.5V to the FR circuit from the B cable, you fried the voltage regulator.
The alternator FR pin behaves like a variable ground. However, the FR circuit is only rated for 5V. When you applied 14.5V to the FR circuit from the B cable, you fried the voltage regulator.
If it behaves as a ground, why does the wiring illustration posted here say to connect to Ign+ with a 1k resistor? ... wouldn't that fry the resistor?
Last edited by HondaInDaBuick; Oct 6, 2020 at 10:56 AM.
The ECU provides 5 reference volts to the Alt FR pin, where the Alt voltage regulator provides variable (duty cycle) ground depending on the amount of load on the car's electrical system. The resulting drop in reference voltage is detected by the ECU, which compensates for the high electrical load by increasing the engine idle speed.
The ECU provides 5 reference volts to the Alt FR pin, where the Alt voltage regulator provides variable (duty cycle) ground depending on the amount of load on the car's electrical system. The resulting drop in reference voltage is detected by the ECU, which compensates for the high electrical load by increasing the engine idle speed.
Thanks.... so what you are saying id there is no way to run this alternator without an ECU?
Thanks.... so what you are saying id there is no way to run this alternator without an ECU?
I am not absolutely sure, but it is quite possible that the 5 reference volts from the ECU are completely dispensable for the alternator to charge the electrical system. The only alternator function that may be lost could be the ability of the ECU to compensate for a high electrical load via increased engine idle speed.
In my previous post, I wrote "To function, the Honda alternator requiresthree wires to be connected".
I would now revise this statement to "To function as intended by the manufacturer, the Honda alternator requiresthree wires to be connected".
I am not absolutely sure, but it is quite possible that the 5 reference volts from the ECU are completely dispensable for the alternator to charge the electrical system. The only alternator function that may be lost could be the ability of the ECU to compensate for a high electrical load via increased engine idle speed.
In my previous post, I wrote "To function, the Honda alternator requiresthree wires to be connected".
I would now revise this statement to "To function as intended by the manufacturer, the Honda alternator requiresthree wires to be connected".
Thanks... I appreciate it.
I am now trying to pull the alternator apart to see if I can bypass regulator and rig an external regulator... but I can't get the armature out... something on the regulator end is locking it in there.
Sadly, I spent over $200 and countless hours building the bracket to fit the 92-00 Civic Alternator... I must find a way to make it work.
Since the stator has 4 leads, it should be the Wye style stator. One of the four stator leads should be the neutral junction. The neutral junction can be identified by more strands of wire when compared to the other stator leads.
The voltage induced across the stator coils is AC voltage. It is converted to DC voltage via the rectifier diode bridge to be able to charge the battery.
Each of the three stator lead ends are connected to respective separate sets of diodes. The rectifier diode bridge on your alternator has 9 diodes. This image is the part of the circuit for the alternator you have.
Were the B cable and IG wire to your alternator properly installed into your car's electrical system? If so, the extremely high voltage output (18V) by your alternator points to a failed voltage regulator. The failure may have been caused entirely or in part to you connecting the IG power source to the FR terminal. Are you able to source a replacement voltage regulator for the alternator?
Since the stator has 4 leads, it should be the Wye style stator. One of the four stator leads should be the neutral junction. The neutral junction can be identified by more strands of wire when compared to the other stator leads.
The voltage induced across the stator coils is AC voltage. It is converted to DC voltage via the rectifier diode bridge to be able to charge the battery.
Each of the three stator lead ends are connected to respective separate sets of diodes. The rectifier diode bridge on your alternator has 9 diodes. This image is the part of the circuit for the alternator you have.
Were the B cable and IG wire to your alternator properly installed into your car's electrical system? If so, the extremely high voltage output (18V) by your alternator points to a failed voltage regulator. The failure may have been caused entirely or in part to you connecting the IG power source to the FR terminal. Are you able to source a replacement voltage regulator for the alternator?
Yes, B+ and IG+ were correct.
The alternator functioned fine at solid 14.5v for a few minutes, then fluctuated 13-18v
I am going to order another new alternator... run it and see if it fails the same.
After reading reviews of the retailer of this alternator (DB Electrical) and discovering they have zero tech support/knowledge, I believe their product may have been defective.
Does it look like lead #2 is neutral? It is in continuity with #1...
#2 is most likely the neutral due to the wire winding around it.
If you get a replacement alternator, you probably can just wire in the IG wire and B cable. There is a thread on H-T regarding using a Honda alternator without ECM for a race car.
Alternator with no ECM/ECU
