No ready, hv battery cooling fans full at ignition on

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Tanemer

Member
Joined
Feb 3, 2025
Messages
9
Hello,
I need help with troubleshooting a fault on my imiev.
What happened:
Day 1. I was diagnosing water heater and mesuring heater coils current. So was repeatedly turning ignition on then ready and then off again to change mesuring from coil to coil. After few rounds it did not go to ready any more. At ignition on red battery icon stayed on, yellow car icon with ! mark also. So tought that 12v run out of juice. It was mesuring 12,2 v so not bad, but charged it aniway. After chargin 12v battery, still nothing. (My hv battery had just ended charging, so that was 100% full before i starter testing on water heater.) Dried to charge hv, it did not work. Remote heating and cooling did not work.
Syptoms- no ready, no heater, no ac, no charging, no clunk on hv contactors.
Raidio worked, lights worked, cabin ventilator worked, ignition worked. Car Scanner showed all sensor values and hv battery cell values but could not read error codes, timed out. After few attempts on ecu, finaly managed to give no error codes found.
Took 12v battery negative lead off for the night.
Day 2. Connected negative lead, ignition on and all lights on dash are glowing and stay so, hv battery ventilation is at full blast, hv battery scale is 0% and charge light flashes. Proxymity sound is on, if i push brake then it goes away. Radio works, no ac, no heating, no cabin ventilator, no ready, no clunk on hv contactors. If i connect charger, then hv battery vetilator kicks in for a second with yellow car on dash, then stops. No charging, no connection to car from diagnostic tools by obd. When preheating/ cooling is turned on, then hv battery ventilator kicks in for a second and then silence.
Took 12v neg. lead and hv safety plug off for night.

Hope, that someone can gide me to fixing this rather strange issue.

Tanel
 
What is the age and condition of your 12V battery? An old, weak or worn out battery will cause a multitude of weird issues such as you are having. Check and verify the capacity of the battery, and replace it if not up to spec. Keep it fully charged at all times for best results and lifetime.
 
Hello and welcome to the forum
Day 1. I was diagnosing water heater and mesuring heater coils current.
I don’t believe in coincidences, therefore let’s get back to the start, how exactly did you measure the HV heater coil current?
Hope, that someone can gide me to fixing this rather strange issue
As @kiev mentioned, might be best to replace the 12V aux, if just to rule it out.

Error lights on the dash usually result in DTCs, if your dongle is still connected, remove it and try it in another car.
 
What is the age and condition of your 12V battery? An old, weak or worn out battery will cause a multitude of weird issues such as you are having. Check and verify the capacity of the battery, and replace it if not up to spec. Keep it fully charged at all times for best results and lifetime.
Thanks for fast reply,

12v battery is of unknown age. It was on charger at night and fully charged when i started day 2. Showed 12,9 v when fully charged.
Just in case i ordered new and should get it tonight, i have a battery tester so can check the old one for capacity also. So will get back with that info in the eavening.

Tanel
 
Hello and welcome to the forum

I don’t believe in coincidences, therefore let’s get back to the start, how exactly did you measure the HV heater coil current?

As @kiev mentioned, might be best to replace the 12V aux, if just to rule it out.

Error lights on the dash usually result in DTCs, if your dongle is still connected, remove it and try it in another car.
I disconnected coil wires from circuitboard and then connected tester between the coil wire and terminal. Ignition/ start was turned on/off as i moved tester between coils. Mesured amps- ign. off - changed cable terminals on tester- ignition on/ start then mesured resistance - moved to next coil and same secuence of mesuring.
I was under the car, heater cover opened. My dad was in the car turning the key. So the key was turned rather rapidly as i didnt have to climb out under the car.
Tryed 2 dongles and Delphi, none of them could connect to imiev. Will try with another car today, will post back with result.

Tanel
 
Last edited:
I disconnected coil wires from circuitboard and then connected tester between the coil wire and terminal. Ignition/ start was turned on/off as i moved tester between coils. Mesured amps- ign. off - changed cable terminals on tester- ignition on/ start then mesured resistance - moved to next coil and same secuence of mesuring.
I assume you measured resistance with the car off and current when in READY?
What values (current/resistance) did you get for the three individual resistors?
Tryed 2 dongles and Delphi, none of them could connect to imiev. Will try with another car today, will post back with result.
Were you able to connect to the car with these dongles before the trouble started? Triplets are ‘fussy’ in that department, best chances of using ‘low cost’ Bluetooth dongles seem to be in combination with the Hobdrive app (paid version for Android)

Just in case i ordered new and should get it tonight, i have a battery tester so can check the old one for capacity also.
Make sure you charge the new battery over night before you install it, it could have been on the shelf for a while…
 
I assume you measured resistance with the car off and current when in READY?
What values (current/resistance) did you get for the three individual resistors?
Yes, you are correct :D ....sorry for misleading information there. Resistance was measured ignition off.
About the resistors, there is something to be noted- All say its PTC heater, but resistance goes down as current rises. For example on one resistor 12 kohms of resistance was 0,6A @ 358V then after about 1 min 30 sek it was 1,5 kohm and 2,5A @358V. So i tought that it is a NTC resistor thats controlled by BJT transistor.
My heater was not heating enough, all elements had resistance, climate switched all 3x inputs on, all resistors where turned on, but heating was not good. Thats why i dived into it and measured the current also.
Were you able to connect to the car with these dongles before the trouble started? Triplets are ‘fussy’ in that department, best chances of using ‘low cost’ Bluetooth dongles seem to be in combination with the Hobdrive app (paid version for Android)
I have Vlinker MC dongle, Car Scanner app developer said its one of the good ones. Jes i was able to connect before trouble started. Used to measure heater temp and resistors switching with it. After first " no ready" i could still connect and see sensor values...HV batt cells were all nice 4,07v - 4,08v..had trouble connecting to ecu. On Day 2. could not connect..no sensor nothing, app tryes 3x and then says no connection. Delphi says also, that it could not connect to car.

New 12v battery has been on charger since lunch today. Old one charged at night from day 1 to day 2. So was fully charged on start of second day.
 
Checked old 12v battery, was also over night charging, and tests ok. Installed new battery, same results. Both 12v batterys have same voltage drop at set current and are ok.
Problem still present when ignition on- hv battery ventilator on, proximity humm on, lights on, dashboard has all lights illuminated and hv battery shows 0%, no ready, havac controls not working, cabin ventilator not working, no connection by obd, no hv battery clonk, no signs of hv anywhere, no charging or preheat/ cool.

I think there is high current draw from 12v battery, becouse when ignition on voltage drops rather fast to below 12v.

Tanel
 
Yes, you are correct :D ....sorry for misleading information there. Resistance was measured ignition off.
About the resistors, there is something to be noted- All say its PTC heater, but resistance goes down as current rises. For example on one resistor 12 kohms of resistance was 0,6A @ 358V then after about 1 min 30 sek it was 1,5 kohm and 2,5A @358V. So i tought that it is a NTC resistor thats controlled by BJT transistor.
Not sure I follow your example, 12kOhm resistor (measured with the car off??) dropped to 597Ohms (358V/0.6A) when on and 90s later to 143Ohms (358V/2.5A). Did you actually measure the voltage across the resistor?

My heater was not heating enough, all elements had resistance, climate switched all 3x inputs on, all resistors where turned on, but heating was not good. Thats why i dived into it and measured the current also.
Taking your example, 2.5A x 358V is about 900W, all 3 resistors at full power should be close to 5KW, do you have the measurements for the others?


I have Vlinker MC dongle, Car Scanner app developer said its one of the good ones. Jes i was able to connect before trouble started. Used to measure heater temp and resistors switching with it. After first " no ready" i could still connect and see sensor values...HV batt cells were all nice 4,07v - 4,08v..had trouble connecting to ecu. On Day 2. could not connect..no sensor nothing, app tryes 3x and then says no connection. Delphi says also, that it could not connect to car. I think there is high current draw from 12v battery, becouse when ignition on voltage drops rather fast to below 12v.
Yes, it seems somehow your method to measure heater current created a permanent, high load to the 12V circuit, that prevents the HV contractors from pulling in

I would start looking around the heater control or areas you ‘disturbed’ to see if there is anything suspicious, a thermal camera could be of great help to identify hot spots.

Measure your battery current and try isolating (fuses) different sub-circuits until you find the ‘culprit’…
 
Not sure I follow your example, 12kOhm resistor (measured with the car off??) dropped to 597Ohms (358V/0.6A) when on and 90s later to 143Ohms (358V/2.5A). Did you actually measure the voltage across the resistor?
For example: 12kohm resistants has one heating element in waterheater ( there are three), measured from one end to another of from this element. Then i turned the heater on and measured current wich was on this element 0,6A @ 358V on the start. After 90s the current had climbed to 2,5A @ 358V. Then i turned heater off and measured resistance again wich was 1,5kohm. Voltage was measured at the power input of elements, not every element separately as i did for current.

Taking your example, 2.5A x 358V is about 900W, all 3 resistors at full power should be close to 5KW, do you have the measurements for the others?
Jes i have, did the measurements again today :D, but was interested only of full power, so measurements are as taken at heater full power and after amps did climb anymore. Element wires are colored as:
White - 2kohm and max current 3A @ 350V
Blue - 2kohm and max current 1,3A @ 350V
Yellow - 1kohm and max current 3A @ 350V

So somehow my heater only buts out 2,555 W - Thats what i was initially investigateing. Diagnostics says max power ~6000w, books say 5000w. Either way half is missing. I think one or two transistors are at fault and not allowing enaugh current to pass through them. Or the elements / resistors are actually cooked. Dont have any information to compare my findings.
 
Kiev and MickeyS70, as you may assume from my previous post, then the car is working again :D .

I checked all fuses except HV battery mains from the battery itself. I opened Inverter and checked hv fuse, i opened DC/DC converter and checked blown caps. Measured ignition switch signals and ongoing currents to fuses. Hoping, that i will find something similar to others who have posted problems with no ready and charging problems.
Then got thinking abut no OBD connection......hmmm...EV ECU? So took the wiring scematics of EV ECU and started to measure all relevant signals that power it up. Finally found, that the EV ECU socket 106 pin 24 and 9 had no power. This is switched via EV ECU relay wich turns on when EV ECU socket 106 pin 2 sends power for coil. Output signal from pin 2 was there. So i tested all contacts of EV relay at relaybox under the bonnet, everything was ok. Took the realy and tested it out from relaybox. The coil was ok.. klicking hard and loud but contacts had no connection. Took full beam relay and swapped it to ECU relays socket. Turned ignition on and all good...no hv battery cooling fans no humming of proximity but no Ready still. Connected diagnostics, cleared all faults from all the different ecus. Ignition off.......ignition on....start...READY :D. All works as intended.

MY FAULT WAS CAUSED BY BAD EV ECU RELAY

I think it just cave up on us, from age or the frequent switching.

Thank you all

Tanel from Estonia
 
Well done on finding the faulty relay…
, but was interested only of full power, so measurements are as taken at heater full power and after amps did climb anymore. Element wires are colored as:
White - 2kohm and max current 3A @ 350V
Blue - 2kohm and max current 1,3A @ 350V
Yellow - 1kohm and max current 3A @ 350V

So somehow my heater only buts out 2,555 W - Thats what i was initially investigateing. Diagnostics says max power ~6000w, books say 5000w. Either way half is missing. I think one or two transistors are at fault and not allowing enaugh current to pass through them. Or the elements / resistors are actually cooked. Dont have any information to compare my findings.
Did you monitor the water temperature, the heater reduces power automatically once it reaches a set point?

On the other hand someone reckoned that almost all triplet PTC heaters (incl. pre-loved ones) are faulty by now??
 
Well done on finding the faulty relay…

Did you monitor the water temperature, the heater reduces power automatically once it reaches a set point?

On the other hand someone reckoned that almost all triplet PTC heaters (incl. pre-loved ones) are faulty by now??
Jes, i monitored heater power request with diagnostics and tried to keep water temp as low as possible for max power demand.
Just have to figure out how am i able to tell if element/ resistor is faulty or transistor controlling it. Havent heard, that NTC/PTC heating element goes this way, that it does not make peak power...or do they. Thats why i think transistors are giving up.
I have heard also, that most of used heaters are somewhat dead or not as intended.

Tanel
 
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