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Old 04-18-2012, 05:05 PM   #1
TheWiltz
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Default diagnositic test shows B+ M- is always 37v?

hello all,

has some time to mess with the carts today 03 and 04 ezgo txt. was running Scottyb's "ezgo diagnostics" as stickied above, and while testing the ITS he says the M- to B+ voltage should be 0 the climb to battery voltage. well mine is ALWAYS at 35 volts then climbs to 37 volts (battery voltage) when i press the gas.(yes i know its not the gas).

thanks in advance.

also just to skip ahead how would i connect the batteries directly to the motor to see if it spins in forward and then reverse?


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Old 04-18-2012, 05:31 PM   #2
scottyb
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Default Re: diagnositic test shows B+ M- is always 37v?

Check the power output from the controller by connecting the negative probe to the controller's M- terminal and positive to the B+ terminal. Press the accelerator and watch to see if the voltage increases. It should increase from a reading of 0 to the full voltage of the battery. If the motor is not turning, the problem may be in the directional switch or motor. The controller is bad and must be replaced if there is no voltage.
I probably should mention controller test is done with at least one rear wheel jacked off the floor and key on, directional selector in forward. ~ test leads on B+ and M- should read 0v then push the gas and watch the voltage rise to full pack voltage?
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Old 04-18-2012, 06:07 PM   #3
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Default Re: diagnositic test shows B+ M- is always 37v?

If there is some conductive crud on the controller between M- and B-,and you are using a high input impedance DVM, you might get a relatively high voltage reading with the pedal up and then full battery pack voltage with the pedal down. Or if there is a leaky MOSFET between B- and M-, you might get those voltage readings.

You could go directly across the MOSFETs by attaching the DVM leads to B- and M-. The reading when the pedal is pushed just far enough for the solenoid to click, should be battery pack voltage and it should to decrease to nearly zero volts with pedal on floor.

Connecting battery pack directly to motor isn't a good idea. The continuity of Motor brushes, armature coils, stator coils and F/R switch contacts are checked by above test.
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Old 04-18-2012, 07:46 PM   #4
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Default Re: diagnositic test shows B+ M- is always 37v?

The connections between B+ B- and M- are clean. I washed the carts before I got started anything (as far as that goes If anyone ever offers you a cart that has spent its life on limestone pass it up. More rust than metal. )

I understood how to do the test Scottyb (and your post is white and very hard to read) but at All times F,N,R I get 35 volts with the positive lead on B+ and the negative lead on M- the voltage does go up to full batt voltage 37v when I press the pedal.

As far as directly connecting the battery to the motor I figured this would not be a good thing but I was figuring the controller is bad and would like to just briefly spin the motor to see if it does spin. The carts are in bad enough shape to make putting batteries, controller and motor in, out of the question. So far I have $3.24 (distilled water) into the carts so my desire to throw $1500 into some rust bucket is not very high. I'd like to just see if the motor turns by bypassing the controller.
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Old 04-19-2012, 03:51 AM   #5
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Default Re: diagnositic test shows B+ M- is always 37v?

Quote:
Originally Posted by scottyb View Post
Check the power output from the controller by connecting the negative probe to the controller's M- terminal and positive to the B+ terminal. Press the accelerator and watch to see if the voltage increases. It should increase from a reading of 0 to the full voltage of the battery. If the motor is not turning, the problem may be in the directional switch or motor. The controller is bad and must be replaced if there is no voltage.
I probably should mention controller test is done with at least one rear wheel jacked off the floor and key on, directional selector in forward. ~ test leads on B+ and M- should read 0v then push the gas and watch the voltage rise to full pack voltage?
I thought this was a blank post 'til I saw it was written in invisible ink!

If folks highlight it, they can read it.
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Old 04-19-2012, 03:35 PM   #6
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Default Re: diagnositic test shows B+ M- is always 37v? now with pictures!

ok frustrating is way to small a word at this point.

i have attached a picture to show that i am getting (on this cart) 28.96 volts when testing from B+ to M-? what gives? i get 37v on one cart and 29v on the other but it should be 0v?

this is what im getting when i run scottys diagnostic:
(i am using 3 12v in series to get my 36v, i have removed the key switch and just connected the 2 wires. - this info just to not leave anything out)


Testing of the EZGO ELECTRONIC SPEED CONTROL - SERIES & PDS (NON DCS)
ALWAYS DISCONNECT THE NEGATIVE BATTERY CABLE BEFORE REMOVING CONTROLLER COVER. RE-CONNECT CABLE AFTER COVER IS REMOVED.
These test are to be conducted after making sure all wires and connections are clean and tight.
PLACE THE REAR OF THE CART SECURELY ON BLOCKS OR JACK STANDS FOR SAFETY
Connect (-) probe of meter on Battery Pack Negative (-) post. (This probe will on the post for the rest of the testing procedures) Connect (+) probe to the Battery Pack Positive (+) battery post. (This reading is the Battery Voltage and the amount of POWER TO THE CONTROLLER -
***37.4volts***

NOW, Key switch ON, gear selector in FORWARD, Place the (+) probe on the battery side of the solenoid's large post (If the reading is below battery voltage, check all wiring and terminals).
***37.4v***

Place the (+) probe to the controller side of the solenoid's large post. The reading should be 0.1 to 3 volts less than battery voltage. If the reading is more than 3 volts less the battery voltage, the resistor is faulty. If the voltage is the same as the battery voltage, replace the solenoid.
***37.2v***


ITS - INDUCTIVE THROTTLE SENSOR

With the key switch ON - Forward direction selected - Push the Accelerator pedal just enough to activate the solenoid.
Install a "jumper wire" between the batteries BL+ post and the solenoid post with red wires attached.
AT THE SIX PIN CONNECTOR OF THE CONTROLLER
Place the (+) probe on the red wire terminal of the connector.
If battery voltage is not present, the red wire between the solenoid and the six pin connector is faulty.
***37.2v***

Place the (+) probe on the black wire terminal of the connector.
The reading should be slightly above 14 volts but than 15 volts. If the voltage is not correct, the Throttle Sensor MAY be faulty.
###14.0v###is this a problem?


Separate the 6 pin connector (only 4 are used) between the pedal box and the controller that's located on the passenger's side of the battery compartment.

???? THIS PART I DONT UNDERSTAND: "IF THE VOLTAGE GOES TO 14..." Where im i testing the voltage????
If the voltage goes to 14 volts, the sensor is faulty.
If the voltage remains below 14 volts, the controller is faulty.

RECONNECT the 6 pin connector.
Place the (+) probe on the white wire terminal of the six pin connector.

***when placing the probe i get .46v.***

Depress the pedal slowly. The reading should be 0.45 - 0.53 volts just as the micro-switch is activated.

***when micro switch clicks i get .54v***

Depress the pedal slowly to full throttle.
As you depress the peddle the reading should move smoothly to about 1.5 volts.

***full throttle 1.6v***

If the reading is incorrect, The Throttle Sensor is defective.
REMOVE THE JUMPER WIRE AND (-) PROBE
CHECKING CONTROLLER OUTPUT Connect (-) probe to M- terminal.
Connect (+) probe to B+ terminal.
The reading should indicate approx. 0 volts.
Slowly depress accelerator pedal.
The reading should show the voltage increasing to battery voltage when fully depressed. If the voltage is at or near battery voltage and the motor is not turning, then the problem lies in either the forward/reverse switch, the wiring, or the motor.
If the voltage increases by a few volts and then stops changing while the pedal is being depressed, remove the orange wire at the "Reverse Micro switch".
If the voltage is not at or near battery voltage, replace the controller.
If battery voltage is present, the problem lies in the reverse circuit.
Re-connect the orange wire.

*** here is where things get even more weird. when connected to M- and B+ I get 28v (see picture) when the solenoid clicks i get 37.4v - full batt voltage- then as i depress the pedel the voltage drops! motor will not turn. ( have connected the batt to the motor and the motor does work)***

i know this is a lot a info but im at my wits end! I can usually figure things out but this cart stuff is killing me.

2 more things:
1- is there a diognostics for the FNR switch.
2- the Series motor wiring diagram i have has a wire connected to A2 on the controller. i do not have a terminal at A2 just a plastic bump?

Thank yall so much for the help.

oh, here is a little story: i was testing voltage all over to figure this thing out. i put my probe down then picked it up to test more. NO voltage, NO VOLTAGE ANYWHERE!!! WTH!!! I checked for a minute and a half before i realized i had my pen in my hand and not my Positive probe...
Attached Images
File Type: jpg controller test2.jpg (169.5 KB, 0 views)
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Old 04-19-2012, 06:49 PM   #7
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Default Re: diagnositic test shows B+ M- is always 37v?

I'll repeat what I said earlier. Either there is a conductive path between M- and B- terminals (IE: The brownish layer of dust shown in the picture) or one (or more) of the MOSFETs electrically located between M- AND B- are leaking.
You are using a high impedance DVM (probably 1 Megohm), so it would only take a leakage current of 28.96 Microamps (0.00002896 Amps) to give you that reading.
If you don't believe it, disconnect the battery and put an Ohmeter between B- and M-.
If you read any ohmic value at all, it will cause your DVM to read something higher than zero Volts when measuring between M- and B+.
I used to mess with student's minds with this phenomena when I was teaching troubleshooting.

Download the service manual from the stickies. (The three *.pdf file are the Service, parts and owners manuals)
http://www.buggiesgonewild.com/elect...g-manuals.html

The troubleshooting tree for a series cart starts on page E-4
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Old 04-19-2012, 07:00 PM   #8
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Default Re: diagnositic test shows B+ M- is always 37v?

It's not that I don't believe you, I am just new to this and trying to figure this out. Yes I had said the controller top was clean. But that was on the other cart I switched carts and forgot to clean the top of this one. I'll try this tomorrow. I figured out today that the S1 and s2 motor wires were put on wrong. Would this cause the problem I'm having or cause things to burn up? They did this on both carts and I'm having the same issue on both carts.

Thanks
again for the help.
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Old 04-20-2012, 12:22 AM   #9
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Default Re: diagnositic test shows B+ M- is always 37v?

If the S1 and S2 cables are reversed, the cart will go backwards when F/R is in F and forwards when F/R is in R. The motor rotates in the opposite direction when current flow through Stator (or Armature) is reversed.

Attached is a drawing of the high current circuit of a generic series cart.

Basically, there is a single current path starting at B+ on the battery pack, through the solenoid contacts, through the armature windings (via a set of brushes), through the F/R switch, through the stator windings and then through the controller (via a dozen or two MOSFETs in parallel between M- & B- terminals) and ends up at B- on the battery.

The only difference between Forward and Reverse is the direction of current flow through the stator.

As noted on the drawing, the A2 terminal on the controller isn't always used.

The controller in the drawing is a Curtis 1204 while you've got a Curtis 1206 but they both work the same.

The speed controller controls the speed by limiting how much current the motor can draw. It does that by turning some electronic switches (MOSFETs - Metallic Oxide Field Effect Transistors) on and off about 18,000 times a second. How long the switches are on versus how long they are off (Duty Cycle) determines how many Amps the motor gets to draw. The technical name is Pulse Width Modulation (PWM).

The aforementioned MOSFETs are physically located between the controller's B- and M- terminals.

The throttle input to the controller tells the MOSFETs how long to stay on. or in other words, how wide the DC pulses are. The MOSFETs are fully on or fully off, so the voltage of the pulse is equal to the battery pack voltage, but your meter averages it, so a low duty cycle reads a low voltage and as the duty cycle increases, so does the average voltage.

If you connect your DVM between B- and M-, your are measuring the voltage drop across the MOSFETs. When the solenoid first click, you should be reading within a few millivolts of the battery pack voltage.

If you are, you have a conductive path from B+ at the battery through the solenoid, armature windings & brushes , F/R switch, stator and every high current cable all the way back to B- on the other side of the battery pack.

If you aren't, trace the path back towards B+ until you find it.

When you get full pack voltage between B- and M- press the throttle. Voltage should decrease to near zero, The voltage drop across a conducting MOSFET is only a few hundredths of a volt, but the duty cycle may be less than 100% and you'll read some voltage if the throttle isn't telling the controller to turn them on 100% of the time.

To check the throttle (ITS - Inductive Throttle System)
Press throttle until solenoid just clicks.
B- to Pin-2 (black wire) should read 9.0V to 11.5V (Voltage source for ITS)
B- to Pin-1 (white wire) should read 0.4V to 0.6V (ITS output telling controller how far to turn on)
Press throttle to floor
B- to Pin-1 (white wire) should read 1.5V to 1.7V

Let us know what you find.
Attached Images
File Type: jpg Hi Current Circuit - Series Motor - EDITED.JPG (63.6 KB, 0 views)
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Old 04-20-2012, 10:05 AM   #10
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Default Re: diagnositic test shows B+ M- is always 37v?

JohnnieB thanks for all the help I am determined to figure this out!
you have been agreat help in understanding how things work.


Quote:
Originally Posted by JohnnieB View Post
If you connect your DVM between B- and M-, your are measuring the voltage drop across the MOSFETs. When the solenoid first click, you should be reading within a few millivolts of the battery pack voltage.

**here I am reading 8v with out touching the gas. after first click of solenoid i read -0.29v and as the gas is pressed im going to 0.0v**


To check the throttle (ITS - Inductive Throttle System)
Press throttle until solenoid just clicks.
B- to Pin-2 (black wire) should read 9.0V to 11.5V (Voltage source for ITS)
**13.97v here**
B- to Pin-1 (white wire) should read 0.4V to 0.6V (ITS output telling controller how far to turn on)
**.54v here**
Press throttle to floor
B- to Pin-1 (white wire) should read 1.5V to 1.7V
**1.6v here**

Let us know what you find.
also i cleaned the heck out of my contorller and imstill getting 28v across B+ and M-. i aslo, just to double check. used an analog vm and still got the same voltage across B+ and M-

thanks again
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