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Discussion Starter · #1 ·
I recently installed a grid charger in my HCH1. When I got to the part where I needed to power up my fan, I quickly became confused by the 4 wires going to the fan. In my fit of rage, I applied 12v to any and every wire I could find, including the ground and PWM wires going back to the ECU. Now I'm in the market for a functional ECU... Does anyone know which parts are compatible with 1K000-PZA-A04 (2005 5-speed)? I've seen some ECU's from others years on ebay for pretty cheap, but am hesitant to buy one that may not work. Does anyone have a schematic for the ECU itself and know which transistor I fried? Any help would be appreciated.
 

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Oh Dear. :(

As you have discovered the HCH1 fan is intelligent and can't be powered up by the simple application of a 12v supply. It's a hi power fan and needs a 12v higher current supply and a pwm signal to control the speed etc. Jeff652? on here sells a special gizmo to power the HCH1 fan with a grid charger.

Now you are asking about the ECU, but do you really mean the MCM which is the silver 8" square box in the IPU compartment which sends control signals to the fan or the ECM which is at the front of the car behind the glove box.

I suspect you mean the MCM. No one has a full schematic for that, but the workshop manual does contain some details and may show a transistor on the relevant output from the MCM. I don't have access to mine at the moment others on here may be able to oblige with a scan/pic.

You say you now need a new computer, did it let out smoke or do you now have an error code etc, what code do you have?
What makes you think it is damaged. They are very tough with well protected I/O.

The parts in the MCM are tiny surface mount jobies. You may if you are very lucky be able to trace the MCM pwm fan control wires back on the MCM pcb for a short distance, and if the gods are smiling on you, you may find the relevant transistor. It's likely a simple npn type, so something like a 2N3904 or BC337 may work if you can't identify it's exact type from any markings it may have.

The difference in the variations for the MCM programming are quite subtle but basically any MCM from a manual car of the same model 2003-2005 should work. Don't get hung up on the exact version number.

If you take the top off the mcm and find any damage or identify the relevant transistor please post some good quality pictures so we can advise further and others can also benefit.

Please update the thread with the outcome either way and update your profile with your location, this is an international site someone may live near you who can help.
 

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Discussion Starter · #3 ·
Sorry, you're right, it's the MCM. When I went crazy applying 12v everywhere I smelled an electrical burning smell that was even stronger than my own body odor. Ever since then, my blower fan runs at 100% all the time. I got a schematic of the wiring harness and found where the blue-white wire goes into the MCM, but can't trace it on the circuit board to the faulty transistor. Since I need to buy a new MCM anyway, I figured I have nothing to lose.

When I get a replacement MCM I think I'll be in good shape. I learned my lesson about PWM the hard way and bought a wiring harness from Mike (complete with fan control board) for my grid charger.

Thanks for your reassurance that any MCM from a 5-speed will do. It threw me a little bit since different year HCH1's have different part numbers.
 

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If you still want to do it yourself, it's not hard to rig a 555 to spit out a PWM signal.
 

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If you still want to do it yourself, it's not hard to rig a 555 to spit out a PWM signal.
Forgive my (electronic) ignorance and lack of vocabulary, but are you referring to "It's a hi power fan and needs a 12v higher current supply and a pwm signal to control the speed etc"?

If so, I would be interested in learning or being pointed to the info if posted elsewhere.

Also, what would the req'd specs on the 12V higher current suppy be?
 

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Discussion Starter · #7 ·
John - I can speak to your question about the voltage and current of the blower, but the PWM is still an enigma to me. I understand that the blower requires 12v 2A at full speed. Pink is +12 black is ground, blue is PWM and yellow is tach.

Hope this helps
 

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Forgive my (electronic) ignorance and lack of vocabulary, but are you referring to "It's a hi power fan and needs a 12v higher current supply and a pwm signal to control the speed etc"?

If so, I would be interested in learning or being pointed to the info if posted elsewhere.

Also, what would the req'd specs on the 12V higher current suppy be?
Oh sure, sorry about that.

This page explains the basics of how it works and has a circuit to build a PWM signal from a 555 timer IC. DPRG: A Simple PWM Circuit Based on the 555 Timer

So to run the fan, you'd apply 12v and ground to the power wires, and the output of this circuit to the PWM line (which, according to vtbeer, is blue). In the schematic there's a transistor and motor - you don't need those, we just want the PWM signal out, which is pin 7 on the 555. Run the circuit off the same 12v you use to power the fan, and make sure the grounds are connected.

Although, I'm not sure how high the voltage is supposed to be on the PWM line for the fan, or what the frequency is, so you'd probably want an oscilloscope to check while the fan is on. Or just go for it, that's what I'd do. :p But then you run a small risk of frying something. I would unplug the fan from the MCM so you don't risk damaging that when you try it out.

Now that I typed all this out, it doesn't sound so simple any more... sorry about that. If you do still want to try, I'll help you through it if you have any questions. I've been doing electronics work for quite a long time.

Depending on how much that fan control board from Mike is, you may just want to go with that.
 

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Duty cycle is the ratio of time the signal is high or low - for example, 30% duty cycle will have the signal high 30% of the time and low 70% of the time.

Frequency is how often those pulses occur, or how short or long they are. Low-frequency pulses could be, say, 3 seconds high and 7 seconds low. That's obviously hardly even PWM, but you see what I mean. Higher frequency could be something like 3µs on and 7µs off.

These are just examples obviously, but that's the difference. And retepsnikrep's thread looks to be a good source of information.
 

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Yep, I'm a Hokie.

Does Virginia refer to:

a) University of
b) Commonwealth of
c) The name of your baby's mama?
I'm a Hokie also, along with my daughter. '75 and '05. I'm '75 (not age) if that helps.

My baby's mama would not ever get on the forum. She just asks me why I spend so much time on the computer reading this forum.
 

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Discussion Starter · #16 ·
The difference in the variations for the MCM programming are quite subtle but basically any MCM from a manual car of the same model 2003-2005 should work. Don't get hung up on the exact version number.

If you take the top off the mcm and find any damage or identify the relevant transistor please post some good quality pictures so we can advise further and others can also benefit.
I'm looking at honda parts dealers websites to try to find the part numbers for '03-'05 5-speed's and the part numbers appear to be identical between the 5-speeds and the CVT's within the year, but not between years. And the cost difference is a couple hundred bucks, which makes me wonder how similar they are. Is the hardware the same (within a given year) but they put different software on it depending on which transmission it has?

This is what I found:

'03 HCH1 KA5MT or KACVT
1K000-PZA-405
1K000-PZA-A02
replaced by 1K080-PZA-415

'04 HCH1 KA5MT or KACVT
1K000-PZA-415
1K000-PZA-A03
replaced by 1K080-PZA-419

'05 HCH1 KA5MT or KACVT
1K000-PZA-307
1K000-PZA-A04
1K000-PZA-A06
replaced by 1K080-PZA-315


I know it's backwards, but after I receive the replacement and confirm it's working then I'll try to fix my old MCM and take lots of pictures. Since I need my car to get to work, I'm not bold enough to try to fix it without having a backup plan. My MCM is working perfectly now with the exception of running my battery cooling fan at full speed all the time. While not ideal, at least it failed in a way that is still cooling the battery.
 
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