Freightliner Data Link Fuse

[Jennifer Curtis]

Helloguys, long time lurker first time posting here. I have a 2005 Freightliner Classic w/14L Detroit 60 Series, 10 spd Ultrashift. I get a "No Data Link" alert after the truck is washed even when the hood is kept closed. When I get the alert the Tach, speedo, oil press, coolant temp, and voltage gages all are dead. After sitting 20 minutes or so it all goes back to normal. Fortunately when this happens it still starts and shifts. I have glanced over the connectors and harness and sure don't see anything that would indicate an issue.

I had the dealer look at it and they say they can't find anything wrong, they claim the weather packing on the harness and connectors look good and there are no fault codes stored in memory. I know sooner or later I will run into a rain and not sure what will happen... If any of you Freightliner owners have experienced this or have any good ideas on where to concentrate I would appreciate it.

If you have your manual? There will be a series of ignition key (on off) cycles that will bring you into the diagnostic side and allow you to check current and pre condition codes. It will also allow you to reset the system to get going again if it's not a harmful condition. Using the designated module numbers you will find a problem.

If it were me, I'd be praying to the dialectic grease gods and targeting those connectors already mentioned but for good measure disconnecting every connector (especially those Low/High sensors on the Ac/dryer) and gooping them full of that grease so they "ooze" when reconnected.

I had an International repair tech tell me to spend a Saturday afternoon, remove batt cables and go over every connector I could find and thusly treat with this stuff. I crawled over, under and through that truck with a tube of that stuff, a handful of "Q" tips and never had another issue with contact erosion/resistance issues after doing so.

My first problem was with a spanking new 04 International that lost it's A/C while we were on our way back from a winter in Az and experiencing 100 degrees in the shade in Tulsa Ok. The little round pins (.020" dia ) of the A/C dryer sensors had rusted and broken off. The tech explained they're often the first to go due to the constant hot/cold cycles drawing humid air past the weather seals of the connectors. Goop 'em full of dialectic grease ....no more problems.

@Desert Miner, yes it was a fleet truck. Curious as to why would that matter? Unless there is more than one , the 9 pin is to the left of the driver seat with my directlink brake controller plugged into it.

He's asking about fleet truck, because a lot of them had a Big Brother box installed. It will use the data bus for it's information, and removal can be haphazard sometimes. Any wires left exposed, that can ground out, & tied to the data highway should be removed.

Darryl is spot on. Did you remove any wires?Did you buy the truck with the Directlink already installed? Try disconnecting the direct link at the 9 pin connector and see if anything changes. Do you have anything else connected to the 9 pin?

@DesertMiner, yes I installed the DirectLink after I bought this. the previous owner stated that he also had this condition after washing. It was a fleet vehicle so what do they usually tie into the DLC for?? I did notice when installing the wiring for my cell booster that there is some type of network cable running through the right sill plate on the passenger (disconnected from what seemed to be heading into the sleeper) side not sure what it was for? (Didn't chase the other end down)? I was an auto technician for 22 years, but this is my first HDT so not much experience here... Learning as I go...

Still trying to track this issue down, the big problem until about 4 days ago it would only happen for about 5 minutes after a truck wash then everything would return to normal operation. Running in the rain didn't seem to make a difference either only after a wash.

Last Tuesday on the info display screen "alert no data link" came back on and this time has stayed on, but also noticed the A/C compressor clutch not engaging (coincidence, or related? Didn't notice that before, but it would only last for 5 minutes or less). I hit a pretty good bump Thursday and I felt cool air coming from the dash vents and looked down to see the alert had gone away on the info display screen and the gauges working again for a few more minutes, then the alert came back and the warm air started flowing again! (Makes me think there may be some relation) Tried wiggling wires around in the engine compartment and by the firewall pass throughs, but could not seem to change anything. I need to look at the wiring schematic to see if there are any common connectors they run through, or even a common ground.

The truck would always start, run, shift up and down and speed control would work. Everything seemed to work except the speedo, temp and oil press gauges, and all the mechanical gauges air & fuel seem to work all the time. Inspected chassis grounds and battery connections. Seems to be an issue on the can bus wires somewhere between the engine ECU and the instrument cluster, (especially since the truck starts, runs and shifts). The main cab to chassis ground looks clean and is tight. It may be time to start pulling the dash apart and looking behind there....

I know on a lot of computer controlled vehicle the computer sends out 5v to the sensors and if anything happens to that voltage to change it what comes back to the computer will be wrong. I don't know why but this often seems to be A/C stuff. If there is any insulation missing on the wire it can give the computer fits. I know ona Cummins Dodge it's often the hi pressure A/C sensor wire that has rubbed against the line that will make all kinds of readings wrong. I hope this is of some help. Iddy

After checking pass thru connections and can bus connections in the engine compartment yesterday, all is working well today. Intermittent electronics can be tuff to get to the root cause. We'll keep searching....

Finally a resolution! Having an automotive background, but not a HDT background, I've learned quite a bit about the data link systems on this Freightliner/Detroit diesel truck. Interesting that it has two different data link systems! The J1939 which basically runs the truck engine and transmission controls (and fortunate for me was not the issue or I would have been on the side of the road!) The second data stream is the J1587/J1708 which runs the smart guages, ABS, HVAC, and satellite systems. First this issue showed up only after getting a wash at a truck wash like Blue Beacon, it would last for 10 minutes or so then everything would come back online and never set any fault codes. A few weeks ago this problem showed up for the first time during rain and high humidity and lasted for 4 days unfortunately I had to keep a timeline traveling to an event and couldn't stop to try to isolate at that point (fortunately I could use my GPS for my speedometer). When I did get stopped it started working again! This would never store fault codes either! During the 4 day period of course I noticed that the A/C would not work, knowing that the system was not flat and noticed that the A/C compressor clutch was not engaging (found no blown fuse's) figured this was all tied altogether with the data link error I was getting. I pulled apart as many connectors as I could find with the data link, and even opened the wiring loom in the engine compartment and pass through s hoping I would find something either by sight or by wiggling the wiring harness around, but nothing seemed to be an issue here! After a few more days I was at my in-laws for a few days and I stopped down to the local Freightliner Dealer near my in-laws Truck Centers, INC in Mt. Vernon, IL, they were great and let me explain my situation with one of their technicians. He had reaffirmed that it was more than likely a short in the J1578/J1708 data stream and that he had seen lots of engine harness issues on the Century's. He seemed really knowledgeable and I would have loved for him to look at it, but I had to get back on the road to another event. Finally a few more weeks went by when the condition reappeared and did not go away this time and had actually set fault codes! I happened to be in Waco working an event and would be here for a few weeks so I checked out the Freightliner dealer here in Waco, Lonestar Truck Group. I again explained what had been going on to the shop foreman giving him as many details as I could. After our visit he was pretty confident they could figure this out in around 3 to 5 hours, so I decided to let them give it a look. Here is what they found. The high leg of the J1708 data link had shorted to ground. they isolated it to the satellite systems leg on the truck. (Not knowing where all the component and wiring locations are is what made trying to do this myself difficult with my event schedule I have to keep and not having access to wiring diagrams and repair manuals). Well they found a chaffed/corroded section of the harness over the passenger side in front of the door, probably from someone yanking out possibly a qualcomm box! Not sure if that would have been the fleet company that owned this truck originally or the company that customized it for the gentleman I purchased it from? The good news is it is fixed now and the guys here at Lonestar Truck Group did an awesome job getting it done reasonably fast and keeping the cost down for a repair that comes down to time and materials.

Yes, these types of repairs come down to how sharp the individual is doing the diagnostics and their product knowledge of component and wiring layouts. I never would have thought about looking in the location they found the trouble. So glad to have it fixed!

I have a 2007 Freightliner Columbia with exact same issues... The truck crossed through some rain and the data bus went out with all gauges. Just this week we had an auto electrician find a short to the pin connector which was linked to a short in the old Qualcomm system. I'm having to start looking for where the harness is grounding out...

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