2018 T770 multiple codes

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jp84x

New member
Joined
Apr 16, 2023
Messages
2
Hi, I'm having a few issues with my bobcat. Everything mechanically seems to be fine, just throwing a variety of codes listed below. Typically it just beeps at me and otherwise keeps on working. The aux hydraulic is frustrating though as it will stop functioning - given that it is electronic I figure it's just the ecu locking it out? Sometimes I'll get all these if I go over a bump. Most of the time I can shut it down, immediate restart and everything goes back to normal. On the aux hydraulic I seem to be able to get it working if I leave the machine off for 30-45 min.

It's a 2018 T770, 3050 hours, serial AT6315767

H7604 "unknown failure"
M4404 "aux no communication"
H4016 "right joystick no communication"
H3916 "left joystick no communication"
H7404 "main controller no communication"
H7504 "drive no communication"
M3204 "ACS (AHC) no communication to bobcat controller"

Any ideas? Thanks in advance!

John
 

brdgbldr

Well-known member
Joined
Jun 1, 2012
Messages
1,239
Sounds like a wiring issue.

First check and clean all of your fuses and relays. Then make sure your battery connections and all ground points are clean and tight.

If none of that fixes the problem you'll need to look for any rub throughs or pinch points on the wiring harnesses. While checking for those clean all of the wire connectors with something like "WD-40 Specialist Contact Cleaner spray" because just a little moisture getting in those connectors can cause corrosion and shorting.
 

Lee Green

New member
Joined
May 7, 2023
Messages
2
Hi, I'm having a few issues with my bobcat. Everything mechanically seems to be fine, just throwing a variety of codes listed below. Typically it just beeps at me and otherwise keeps on working. The aux hydraulic is frustrating though as it will stop functioning - given that it is electronic I figure it's just the ecu locking it out? Sometimes I'll get all these if I go over a bump. Most of the time I can shut it down, immediate restart and everything goes back to normal. On the aux hydraulic I seem to be able to get it working if I leave the machine off for 30-45 min.

It's a 2018 T770, 3050 hours, serial AT6315767

H7604 "unknown failure"
M4404 "aux no communication"
H4016 "right joystick no communication"
H3916 "left joystick no communication"
H7404 "main controller no communication"
H7504 "drive no communication"
M3204 "ACS (AHC) no communication to bobcat controller"

Any ideas? Thanks in advance!

John
Mine is throwing the same codes and high flow stop often. If you figure it out. I would like to no. You could text or call 479-849-4793 please!!!
 

Lee Green

New member
Joined
May 7, 2023
Messages
2
Hi, I'm having a few issues with my bobcat. Everything mechanically seems to be fine, just throwing a variety of codes listed below. Typically it just beeps at me and otherwise keeps on working. The aux hydraulic is frustrating though as it will stop functioning - given that it is electronic I figure it's just the ecu locking it out? Sometimes I'll get all these if I go over a bump. Most of the time I can shut it down, immediate restart and everything goes back to normal. On the aux hydraulic I seem to be able to get it working if I leave the machine off for 30-45 min.

It's a 2018 T770, 3050 hours, serial AT6315767

H7604 "unknown failure"
M4404 "aux no communication"
H4016 "right joystick no communication"
H3916 "left joystick no communication"
H7404 "main controller no communication"
H7504 "drive no communication"
M3204 "ACS (AHC) no communication to bobcat controller"

Any ideas? Thanks in advance!

John
I also have a 2018 T770 its throwing the same codes. If you get it figured out let me now what it is please. I have been through it and can't find anything
.
 

Equip

Member
Joined
Mar 3, 2023
Messages
9
I'm having the same issues on a A770 as the latter of this original message.
I checked harness plugs and opened up the joysticks and found no serviceable parts as all sealed modules.
some times the Aux controller acts up with codes. same codes as above.
Anyone else come across this?
 

Equip

Member
Joined
Mar 3, 2023
Messages
9
Hi, I'm having a few issues with my bobcat. Everything mechanically seems to be fine, just throwing a variety of codes listed below. Typically it just beeps at me and otherwise keeps on working. The aux hydraulic is frustrating though as it will stop functioning - given that it is electronic I figure it's just the ecu locking it out? Sometimes I'll get all these if I go over a bump. Most of the time I can shut it down, immediate restart and everything goes back to normal. On the aux hydraulic I seem to be able to get it working if I leave the machine off for 30-45 min.

It's a 2018 T770, 3050 hours, serial AT6315767

H7604 "unknown failure"
M4404 "aux no communication"
H4016 "right joystick no communication"
H3916 "left joystick no communication"
H7404 "main controller no communication"
H7504 "drive no communication"
M3204 "ACS (AHC) no communication to bobcat controller"

Any ideas? Thanks in advance!

John
I have been working on A770 units for a bit now and they are very buggy at times.
Maybe my customer just bought some yellow lemons. haha
But when you fix different issues the codes go away.
I currently have the M4404, H4016 and H3916 codes.
I wonder if there are any technical service bulletins out for these machines from the manufacture?
 

brdgbldr

Well-known member
Joined
Jun 1, 2012
Messages
1,239
From what I have learned, most multiple code problems stem from bad connections.

I have worked on machines where the operator has told me over the phone that the battery connections are good. I check them by removing them and find the connections corroded and filthy. Clean them and all the codes disappear. Or the battery wires are not in good condition. Change them out and and the problem goes away.

I'm not trying to say that this is always the case but a lot of time it is.

Also, rub throughs on the harnesses are common especially at factory tie down points. People are reluctant to cut the tie and inspect the wire.

Another factory issue was that they painted the frame at the grounding points and then connected the ground wire. The ground wire needs to be removed and then the paint sanded off to bare steel before reinstalling it.

Another good thing to inspect closely is the auxiliary electrical wire harness. This plugs into the same place as the Techs diagnostic computer, above the battery. If this harness has a short it messes with the machines computer.

I absolutely hate electrical problems on these machines. Everybody says that it's just the nature of hard used heavy equipment but my off-road pickup gets used just as hard and I never have these problems with it.
It's just really poor design and engineering.
 

Equip

Member
Joined
Mar 3, 2023
Messages
9
From what I have learned, most multiple code problems stem from bad connections.

I have worked on machines where the operator has told me over the phone that the battery connections are good. I check them by removing them and find the connections corroded and filthy. Clean them and all the codes disappear. Or the battery wires are not in good condition. Change them out and and the problem goes away.

I'm not trying to say that this is always the case but a lot of time it is.

Also, rub throughs on the harnesses are common especially at factory tie down points. People are reluctant to cut the tie and inspect the wire.

Another factory issue was that they painted the frame at the grounding points and then connected the ground wire. The ground wire needs to be removed and then the paint sanded off to bare steel before reinstalling it.

Another good thing to inspect closely is the auxiliary electrical wire harness. This plugs into the same place as the Techs diagnostic computer, above the battery. If this harness has a short it messes with the machines computer.

I absolutely hate electrical problems on these machines. Everybody says that it's just the nature of hard used heavy equipment but my off-road pickup gets used just as hard and I never have these problems with it.
It's just really poor design and engineering.
Good morning and thanks for your comments.
I will check these areas out you mentioned, sometimes its great to get another tech thoughts when you have too many units to look after almost at once.
I know I have changed some negative cable assemblies out for the battery, but will for sure check other grounding points as I do have all the manuals for these units with schematics as I'm up north.
Cheers
 

2019 T770

Member
Joined
May 19, 2023
Messages
5
I had m4404 and a few others. I first cleaned each fuse and relay. The fuses had corrosion .then I f found an issue that might only be on mine. what I found was the auxiliary controller had a wire that was cut (green fourth from the bottom left to right and the repair on it was not good. I fixed it and checked for continuity. Runs great now.
 

Maindrain

New member
Joined
Apr 25, 2024
Messages
1
T770 Codes H3916 W3276 Replaced both Joysticks, Replaced the Wiring harness , Replaced the Main Controller still Cannot get it running to where I am comfortable in Running it
 

2019 T770

Member
Joined
May 19, 2023
Messages
5
M4404 and other intermittent codes. Went away with a new AUX controller. Thought it was wiring due to the intermittent nature of the problem but nope has to bite the bullet.z trouble free for a year now
 

stick0014

New member
Joined
Apr 23, 2024
Messages
1
Im haveing same issues on a 2019 t770, m4404. It sits for a bit it runs fine no codes, 20 mins of work with hiflow. Shuts down aux hydraulics gives code m4404. And some times throws other random codes. I belive it to be the aux controller (computer) something i assume is getting to hot, and causing it to fail. After sitting and cooling its fine till it over heats again. I first thought bad ground or relay. Which also makes sense. But then ibwoupd assume after sitting for 30 mins, the problem should still be there? I have moved around relays. Didnt change a thing.
 

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