# Curtis 1238 controller error 14 precharge failed



## travellingtechie (Jul 18, 2017)

Hello, first post and first time working on an electric vehicle. I have some moderate motor controller experience from robotics, but nothing like this.

I purchased a Miles zx40St Electric Truck, I was under the impression that all it needed was new batteries, but upon further inspection that appears not to be the case. When I turn it on, I'm getting an error code 14, precharge failed. In searching through old forum entries, I found something about connecting a resister across the main contactor. I'm reluctant to attempt a fix without having a reasonable idea of what I'm trying to accomplish, plus I don't even know what the main contactor is. I'm reasonably smart and willing to do the research to understand what I am doing, but I'm pretty far out of my depth at the moment. 

Can someone provide me with some information on what this error means, what is a precharge, what the main contactor is, and where I go from here? Pointing me to documentation or reading material is perfectly acceptable too. Currently I have the Controller manual and an Electrical Troubleshooting manual for the truck. 

Thanks in Advance.


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## frodus (Apr 12, 2008)

Can you post how you've got it wired?

Precharge on these curtis is done automatically, through the KSI input, pin 1 of the connector on the curtis.


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## travellingtechie (Jul 18, 2017)

I haven't done anything to the wiring to modify how it came with the vehicle. The one document that I have been able to find is this one:
http://www.publicsurplus.com/sms/do...shooting_Manual.pdf?auc=1034394&docid=8691690

page 30 shows pin 1 wired to the charge controller board. What exactly is "precharge"?

Side note, I realized my timing of this question is unfortunate, as I'm going to be out of town for the next 3 weeks. I will pick up this thread when I return and can do some more research on the vehicle.


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## frodus (Apr 12, 2008)

Precharge brings the capacitors inside the controller up to pack voltage before the contactor is closed. It extends the life of your contactor and keeps it from getting welded. Caps have a large inrush current that can damage components.

Pin 1 is KSI, which is where there should be Pack voltage when you turn the car on. This goes to the controller internals, and the controller will then precharge the internal capacitors automatically. DO NOT use a resistor across the contactor, as the controller already does this for you.

I would check that you're getting pack voltage on pin 1 when you turn the car on.


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## travellingtechie (Jul 18, 2017)

Awesome thank you for the information. I'll check that when I return home and post more then.

B


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## travellingtechie (Jul 18, 2017)

I apologize for the delay, but I'm back working on this problem, for a couple weeks at least. So I took a measurement between pins 1 (KSI) and 7 (reference ground) with the key on and got between 48 and 52 volts (I think its supposed to be 72).

I am also getting a different error code now. 
39 Main contactor did not close

I'm still reading through the manual to interpret this one, but thought I'd post what I have so far.

B


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## martinwinlow (Sep 22, 2009)

Hi, A bit late to the party but I have an Aixam Mega City (electric car) with a Curtis 1244 controller. It is unrelated to your issue I expect but I foolishly (apparently) damaged my Curtis a few days ago when I was 'tinkering' with things with the battery pack isolator still closed (thought I had opened it). It now gives the 'Precharge Fault' error. I'll try the KSI test (when it stops raining).

One thing you might try is looking to see if you have this problem (I've had it twice now and it causes the 'Main contactor did not close' or similar "Ooohh! This is a nice warm place for a snooze..." CLACK!!! "Uh oh...")...


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## travellingtechie (Jul 18, 2017)

Thanks for the reply, definitely keep me posted. I've had to shelve this project until after the beginning of the year, but I will definitely be getting back in to it soon.


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## martinwinlow (Sep 22, 2009)

If you are not getting full pack voltage at that point, are you getting it at the entry to the main contactor? It would help if you knew what the pack voltage should be, tho!!!

Let me know when you are back in the saddle with your project and maybe I can be of some help.

In the meantime, I have managed to get the Curtis programming software talking to my 1244. What I really need is someone to help me set it up on the bench with a dummy motor load and a basic 5k pot etc to see what errors the software shows then. I'm going to investigate a possible failure of a component on the pre-charge bit of the PCB (wherever that is). First, I have to get the lower PCB off the heatsinks...


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## kcwb1 (Oct 3, 2018)

Does anyone on here have a picture of how they have wired this up? i am having issues with my precharge on my curtis 1236 and assume its to do with wiring set up


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## martinwinlow (Sep 22, 2009)

I assume you have the Curtis manual (which should show a basic configuration)?


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## dork (Oct 17, 2020)

kcwb1 said:


> Does anyone on here have a picture of how they have wired this up? i am having issues with my precharge on my curtis 1236 and assume its to do with wiring set up
> QUOTE]


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## dork (Oct 17, 2020)

Hope this little note will help you I had the same issues with my 2008 miles pick up acted as if it went into limp mode


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