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speedo/tach nightmare

I have just been checking it with the motor off.

I don't know if it is the same for the early single phase charging systems but on the late models the DTC voltage check (high or low) is viewed by the ECM at 2000 RPM. That would make sense for 3 phase systems but since you are single phase, I would check the voltage at around the 3.5K RPM range.

If higher than normal voltage is present, all bets are off as far as anything making any sense. Electronics become completely unpredictable when higher than normal voltage is present. Back in the old days, higher than normal voltage was deliberately used to crack security codes on electrical locks and smart cards.
So throwing out erroneous DTC's codes could/would be expected.
 
Awesome advice. Thanks a million. Ill keep trucking and nailit down eventually. HD dealer was zero help. Just said "bring it in" abou ten times. BTW, have you guys heard of these early FXDX being buggy with the electronics? I heard they were pretty solid.
 
Awesome advice. Thanks a million. Ill keep trucking and nailit down eventually. HD dealer was zero help. Just said "bring it in" abou ten times. BTW, have you guys heard of these early FXDX being buggy with the electronics? I heard they were pretty solid.

Any thing can and will go sideways with Electricity, H D had lots of problems in the early days with their electronic ignitions:s
 
great news.....

The single best thing you can do to insure a lot of trouble free miles is keep your battery charged, clean and tight connections. Check clean and tighten the main lug on the starter and put a bit of dilectric grease on that connection. Check to make sure you have good grounds:s
 
No bro, that just shows what the rate of charge is, it won't tell you if you have a bad cell in the battery... A load tester will place a load on the battery and if it has a weak or bad cell, it will show up... It's the only way to know for sure if the battery is good or bad... Take care... T

K Tool International 70212 - Hydrometer Battery Tester this will help find a bad cell in a non sealed battery before you load test it:s
 
Ok. Here is the update.....battery is fine. My voltage is in the 16.5 volt range peak. For some inexplicable reason, the speedometer now works. The tach still doesnt. The engine light is not on. Go figure. My voltage regulator is giving me all sorts of weird readings when I put it on the meter. Probably needs to be replaced. Ill check the power to the tach and see what thats reading. Thanks for the help gentlemen. Im not too good with electrics.
 
Not that i am an expert but i am pretty sure if you are above 14.5 volts at peak revs then it is to high and may do all sorts of damage it has probably reduced the life of the battery already
voltage regulator would be where i would be starting as it should be regulating your voltage to not going over 14.5 volts
But Hoople is the expert on these things so lets wait for his words of wisdom

Brian
 
Sounds like the regulator may not be limiting the voltage as it should. Check to see if it's going above 14.5 volts by using a meter and hold the RPM in the 3.5K range.

Yep, regulator is toast. Change it out.
 
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