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I have a fault code 128 231 8 Sid. I looked online and it…

Customer Question
Hi! I have...

Hi! I have a fault code 128 231 8 Sid. I looked online and it says abnormal frequency. What does that mean?

Mechanic's Assistant: What's the make/model/year of your truck? Engine type?

2004 Mack Cx613. The EGR was recently cleaned.

Mechanic's Assistant: Are you fixing your truck yourself? What have you tried so far?

My mechanics are. I unfortunately have limited knowledge of what they have done.

Mechanic's Assistant: Anything else you want the truck mechanic to know before I connect you?

I also am having codes 128 021 9 SID coming up.

Submitted: 3 months ago.Category: Medium and Heavy Trucks
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Answered in 7 minutes by:
3/26/2018
Technician: Wayne, Journeyman replied 3 months ago
Wayne
Wayne, Journeyman
Category: Medium and Heavy Trucks
Satisfied Customers: 11,217
Experience: worked on, Gmc, Macks, Freight liner,Mercedes Benz,,Ford, sterling
Verified

Hi, I’m Wayne.

I will be assisting you with this issue today.

SID 231 IS THE J1939 control circuit, FMI 8 is an electrical fault. So the engine is saying it can't talk to other ECM's or it can't hear them. The twisted green and yellow wires are the data link (J1939) circuit

check pins C & D in the diagnostic plug in the cab

should be yellow and green twisted wire

you want 60 ohms, if more or less the wire is shorted

or broken

I hope this helps you

Wayne

My goal is to give you the best experience possible.

I hope that I have earned a 5-star rating

Found at the top of the screen before you leave today.

If you need more assistance, please use the reply box and let me know.​

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Technician: Wayne, Journeyman replied 3 months ago
MorningJust following up with youDid my answer help youWayne
Ask Your Own Medium and Heavy Trucks Question
Technician: Wayne, Journeyman replied 3 months ago
MorningI took the time to answer your questionsand work with youPlease take the time to respond to meWayne
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