BENDIX EC-80 ATC ABS FAULT

Most common you will find a modulator common shorted somewhere on the ABS chassis harness. Ohm to ground on the chassis harness at the firewall connector. You can usually shake it down to find the rub.

 

Low voltage to ABS module or a bad battery can also cause this FC if you can't find a short to power at all... Same exact issue two weeks ago. Batteries weren't even two months old. It would read about 2 Volt on common until I changed out batteries. One tested shorted cell. Rush Truck Center "special" economy line batteries. We had a weird crank issue on one truck and transmission shifting issues on another because of these batteries.

 

Hey I’m working on a 2014 Peterbilt with an EC 80 abs I’m getting FC 802 fmi 4 modulator commons shorted to ground that’s the only one that comes up from the abs system I started with checking all the fuses for the abs both exterior and interior everything’s all good along with every fuse, and I started to check the connectors for the abs module it has two main connectors I think they refer them to as x1 , x2 “ connectors im checking the “main” connector I believe which is the x1 and I’m getting 2 powers and 2 grounds but for 2 of the other pins I’m getting around 2.9v I think it’s pin 7, 11 but I’ll make sure in a few hours. Any tips or advice would be really helpful and appreciated. I’m leaning towards replacing the abs ecu module. Thank you guys once again!

 

You need to measure the modulator commons for continuity to ground. And shake down the ABS chassis harness to find the short. The ECU is suspect only last after all wiring has been covered.

 

I might of found the problem. I followed the wires back up against the firewall it’s a brown connector right behind the steering column I wiggled the connector and noticed that the connector was making bad connection. I unplugged it cleaned the pins and made sure it clicked in place this time and the problem hasn’t came back. Thank you for the advice!

 

I have 2019 kenworth T680 with bendix esc80
I have the same problem code son 802 FMI 4 short ground. I can’t find any wire touching anything .. battery are new . Any help will be appreciated thanks

 

You need a digital multimeter and you need to check for any shorts between all the common wires for each modulator valve, traction control valve and hill start aid valve if equipped. The ECU is not able to pinpoint which one is bad. Bendix ECUs are very sensitive and even resistance in the milliohms will cause this fault. So you need a good digital multimeter for this and you are testing between each common wire and ground with the connectors disconnected at the ABS. Hopefully you can find one modulator valve is doing it. Then unplug that valve to see if your short goes away. Some valves will short out internally. If not, you are chasing wires. If you know the wire that is causing it, but can't find the bad spot, run a new wire.

 

SPN FMI codes sometimes lead down a frustrating path.
Find the pdf online for the EC 80. On the abs unit under the dash, find pin 18 on block X1. It runs to the dash error light. Wire in a momentary switch to ground. A diagram in the pdf explains. This will give blink codes using the dash abs light. Press once for active codes, twice for inactive and three times to try and clear codes. First blink group is the which wheel, second blink group is the error.