# Zilla Error 1141 Main Contactor High Resistance



## 92 Escort EV (Jul 3, 2008)

Update on eliminating the 1141 error:

I now believe that a shorting speed sensor wire was causing the 1141 errors. Time will tell and I will update this post if the errors seem to have been eliminated. If not I will add a capacitor as noted below.

I had a speed sensor wire rubbing and eventually shorting to ground on my EV, that caused damage to the hairball, (my fault for removing a fuse!). The reason I removed it was that it was an inline fuse and very close to an AC inverter. I thought it might be introducing noise into the speed sensor, causing the 1141error. I replaced it with the original shielded cable that had no fuse in the 12V wire. (I know, Bad, Bad!!!)
The speed sensor only uses 10mA to run so, an appropriate fuse size will protect the Hairball from damage. I removed the speed sensor 12volt wire from the hairball. It now gets its power from a separate 12V source from the hairball. (In other words don’t use the Acc +14V Out on the hairball). With no fuse in the wire, the short to ground caused damage to the hairball that had to be sent in for repair. This was my fault, but can’t happen now that the power is not from the hairball, and now has a permanent fuse. I was also originally using a blade style fuse, and they only go as low as 1Amp. You may need to use a glass fuse that is about 62mA.


As noted in the Zilla Manual:
“Speed sensors are especially susceptible to electrical noise and can benefit from a shielded twisted pair wire between them and the Hairball. We include 6 feet of this wire with every sensor that we provide. Some speed sensors still have problems, even with shielded twisted pair wiring. In those cases I find it helpful to filter the power to the speed sensor by putting a 0.1 microfarad capacitor on the power leads to the sensor. It is important that this capacitor is close to the sensor, within 8" is good.”

I also found the following information from Café Electric and another EV builder who sometimes has this error.

The 1141 errors can come from the ground lead to the speed sensor getting large noise spikes. You could connect the speed sensor ground to the chassis for more safety, (for the hairball, in case of a short), in exchange for more likely noise issues on the speed input (causing incorrect speed reading).

*** My Note: I am not going to do the above at this time. ***


From another EV builder:
I still get the 1141 error myself from time to time. It mostly happens when I'm at very low pedal position and just creeping along and it will just drop out power. All I have to do is flip the key off and back on to reboot the Zilla/Hairball, and everything is fine again. Per emails with Otmar there are a couple likely causes, and he said it mainly had to do with wires being too close to others that carry interference. He also mentioned he had this issue in retrofit Sparrows until some wires were routed differently. Specifically in my case I have my shunt about an inch from the Hairball and this is what Otmar thought was likely the cause of the problem. The other thing he mentioned was interference in the tachometer sender wires could also cause this. He said that the pre-charge wires could also be the culprit. The pre-charge wires are the ones that connect to the two Hairball terminals labeled: Main Cont. Controller + / Battery +.


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## Tesseract (Sep 27, 2008)

92 Escort EV said:


> ...
> I now believe that a shorting speed sensor wire was causing the 1141 errors.
> ...
> As noted in the Zilla Manual:
> “Speed sensors are especially susceptible to electrical noise and can benefit from a shielded twisted pair wire between them and the Hairball. We include 6 feet of this wire with every sensor that we provide. Some speed sensors still have problems, even with shielded twisted pair wiring. In those cases I find it helpful to filter the power to the speed sensor by putting a 0.1 microfarad capacitor on the power leads to the sensor. It is important that this capacitor is close to the sensor, within 8" is good.”


I can attest that getting a speed sensor to work properly in the high electrical noise environment of an EV is _tough_.

In contrast to what is in the Zilla manual, I think you'll get better results if you place the 0.1uF capacitor for the sensor power at the Hairball end, not the sensor end. Furthermore, I think it might prove useful to add a second capacitor from the sensor output pin to ground if the sensor is "active high" or from output to V+ if it is "active low" (aka open collector NPN, which is very common in industrial proximity sensors)... I'd start with 0.01uF (film). Please let us know what you end up trying and whether any of the tricks work.


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## 92 Escort EV (Jul 3, 2008)

Tesseract, 
Since eliminating the short, (speed sensor 12V power grounding to the frame of the car), there have been no 1141 errors. It has been 9 days with no errors. Before I was getting one almost daily. 

I don't plan on installing the capacitor unless I still have problems. 

As for the information you provided/asked about the speed sensor, it is the one cafe electric sells. It says that it pulls the signal wire low 4 times per revolution. I understand the basics of how this works, but I am not well versed in electronics.

Thanks for the information.


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