R.E.D Posted March 22, 2016 Share Posted March 22, 2016 So while I was driving down the road the truck lost throttle.The pedal is completely dead along with the rpm gauge.Fault code is 6-4.I checked the connectors in the abs computer near the injector and the vecu in the cab.both show no corrosion. Also the triangle connector coming out the firewall.truck is idling higher than normal and the key won't shut the engine off until 15 to 20 second after the key is in the off position.Please advice on what further steps can be taken.truck is 98 ch 355hp Quote Link to comment Share on other sites More sharing options...
41chevy Posted March 22, 2016 Share Posted March 22, 2016 From Mack Information System: Blink code 6-4: J1939 serial data line Failure Mode Identifier FMI: 8 (Abnormal) Parameter Identification: S231 Message Identification MID: 128 (Abnormal), 142 (Abnormal) Circuit Description: The V-MAC III system uses the J1939 data line to control communication between the Vehicle Electronic Control Unit (VECU), Engine Electronic Control Unit (EECU), Anti-lock Brake System Control Unit, Allison Transmission Control Unit, and accessory systems, depending on vehicle model and option content. The J1939 data line is an expandable data bus, allowing the addition of accessory control modules (Collision Avoidance, Traction Control, etc.) to be connected to the circuit. The J1939 data line is comprised of two circuits; the L circuit and the H circuit. The two wires are twisted together to prevent outside electrical noise from interfering with the data being carried by the L and H circuits. The V-MAC III system is designed to allow continued engine operation with the loss of the J1939 data line signal as long as the J1587 data line is still operational. Code Setting Conditions: If either the Vehicle Electronic Control Unit (VECU) or the Engine Electronic Control Unit (EECU) loses communication on the J1939 data line for more than one half second, code 6-4 will set and the Electronic Malfunction Lamp (EML) will turn on. The fault will become inactive if communication resumes for at least on half second. When code 6-4 is active, engine speed will default to 900 RPM. If communication is lost on both the J1587 and J1939 data lines the engine will not run. Fault code 6-4 will set for some mismatches of VECU and EECU software levels. Blink code 6-4 will also set while the VECU is in the programming mode for Customer Data, Fleet Data, or Mack Data. This code setting condition is normal and the code will become inactive after the ignition key is cycled. Fault code 6-4 may log, without illuminating the Electronic Malfunction Lamp (EML), on vehicles equipped with Eaton/Bosch ABS/ATC module # 7MN54M2. This nuisance code will not affect the performance of the vehicle. When a vehicle equipped with this ABS/ATC module is being diagnosed for an inactive code 6-4, contact Mack Trucks Service Engineering. Additional Symptoms:If communication is lost on just the J1939 line, the engine will only run at 900 RPM, no throttle response above 900 RPM 1 Quote "OPERTUNITY IS MISSED BY MOST PEOPLE BECAUSE IT IS DRESSED IN OVERALLS AND LOOKS LIKE WORK" Thomas Edison “Life’s journey is not to arrive at the grave safely, in a well preserved body, but rather to skid in sideways, totally worn out, shouting ‘Holy shit, what a ride!’” P.T.CHESHIRE Link to comment Share on other sites More sharing options...
R.E.D Posted March 23, 2016 Author Share Posted March 23, 2016 So which one is the j1939.is it connected to the vecu?or the one next to it?there are two cables that are wrapped individually with some kinda foil on the inside of the plastic lining.they go to a 3 prong connector.are thy it?.is there an easier way to troubleshoot?thanks Red Quote Link to comment Share on other sites More sharing options...
41chevy Posted March 23, 2016 Share Posted March 23, 2016 That is the shielded data link cables ,do not damage the foil as it cuts outside interference with the data stream. . With out a scanner to check the balance of the system, I do not believe there is much you will be able to do aside from checking the connections. Quote "OPERTUNITY IS MISSED BY MOST PEOPLE BECAUSE IT IS DRESSED IN OVERALLS AND LOOKS LIKE WORK" Thomas Edison “Life’s journey is not to arrive at the grave safely, in a well preserved body, but rather to skid in sideways, totally worn out, shouting ‘Holy shit, what a ride!’” P.T.CHESHIRE Link to comment Share on other sites More sharing options...
turckster Posted March 25, 2016 Share Posted March 25, 2016 There are two communication systems in your truck- the high speed j1939 system and the low speed j1587. Look at it as J1939 is cable internet and j1587 is dial-up. If you loose the j1939 to one of the ecu's--either the engine ecu or the vehicle ecu, you will get this fault. If you loose both J1939 and J1587 then the engine will not start. This is a PDF of the diagnostic flow chart for a 6-4 fault: 6-4 diagnostic flow chart.pdf Quote Link to comment Share on other sites More sharing options...
R.E.D Posted March 28, 2016 Author Share Posted March 28, 2016 Thanks for the great info fellas . found the problem to be one of the two sets of cable wrapped with foil . replace it and truck running like champ now. 1 1 Quote Link to comment Share on other sites More sharing options...
Brian logsdon Posted October 24, 2018 Share Posted October 24, 2018 R.E.D. where did you find the j-1939 cable? My mack dealer says it's part of the whole dash harness which is hard to believe, its separate but plastic tied with the harness. I don't see why you can't purchase it separately Quote Link to comment Share on other sites More sharing options...
Macktech689 Posted October 27, 2018 Share Posted October 27, 2018 Keep in mind any loss of voltage or ground to the control modules will log 6-4 also. The fault isn't always in the data link wiring. Fixed a 6-4 fault this week that was caused by engine harness wires rubbing on the block causing the engine module to lose power. 1 Quote Link to comment Share on other sites More sharing options...
R.E.D Posted August 28, 2019 Author Share Posted August 28, 2019 I'm reviving this old tread because I'm having this same issue with the CV.Code 6-4. Last night I was on a job and truck started acting up. At first it seemed like the fitting on top of the oil filter housing had rubbed the insulation on the harness for the ecm.the fitting was kinda eaten up on one corner like if it had been shorting against something. I wrapped up everything in electrical tape yet issue still persist albeit less often than before.also top ecm connector had some oil . would this cause it to loose connection? What's the best way to clean up these connectors and pins? Thanks Red Quote Link to comment Share on other sites More sharing options...
R.E.D Posted August 28, 2019 Author Share Posted August 28, 2019 Found the bottom ecm connector full of coolant and grime.hopefully that solves it Quote Link to comment Share on other sites More sharing options...
R.E.D Posted August 28, 2019 Author Share Posted August 28, 2019 After cleaning.im getting a " no info" on the dash.could the ecm be fried? Quote Link to comment Share on other sites More sharing options...
R.E.D Posted August 28, 2019 Author Share Posted August 28, 2019 Found the issue ..3 ecm pins have completely eroded off ..need a new ecm Quote Link to comment Share on other sites More sharing options...
fjh Posted August 28, 2019 Share Posted August 28, 2019 31 minutes ago, R.E.D said: Found the issue ..3 ecm pins have completely eroded off ..need a new ecm Beleive there is an anti wicking harness for this issue you should invest in it! 1 1 Quote Link to comment Share on other sites More sharing options...
R.E.D Posted August 28, 2019 Author Share Posted August 28, 2019 Quote Link to comment Share on other sites More sharing options...
R.E.D Posted August 28, 2019 Author Share Posted August 28, 2019 Quote Link to comment Share on other sites More sharing options...
Mack Technician Posted August 28, 2019 Share Posted August 28, 2019 (edited) 3 hours ago, R.E.D said: What's the best way to clean up these connectors and pins? Thanks Red That's ugly......R.I.P. ECM For future......I was given a small 5 Oz can of Deoxit D5 by Liehberr. Stuff has been my go to. Hit it with regular No Flash electrical cleaner then Deoxit and reassemble. The machines Liehberr sold have to rotate continuous, so they are running sensitive Serial/CAN lines through a constant rotation brush style electrical connector. That Deoxit is the only stuff that would lubricate/clean/maintain a connection. Regular Dielectric grease lifted the connection stinger off the contact disc and set codes. Get your Coolant Level Sensor Capillary Jumper in there ASAP. I thought all trucks got a free one from Mack? Maybe someone failed to follow up? Your coolant sensor harness wire is also filled with coolant. Edited August 28, 2019 by Mack Technician 1 Quote Link to comment Share on other sites More sharing options...
R.E.D Posted August 28, 2019 Author Share Posted August 28, 2019 It wasnt the coolant sensor dripping.it was the over pressure line thats connected to the pressure cap that was routed and pointing down towards the connectors 1 Quote Link to comment Share on other sites More sharing options...
R.E.D Posted August 28, 2019 Author Share Posted August 28, 2019 Part number seems to be a 12ms530m .there is one for sale used .local mack wants a fortune and not in stock.like always.does the new used one need to be reprogramed? Quote Link to comment Share on other sites More sharing options...
R.E.D Posted August 28, 2019 Author Share Posted August 28, 2019 bought a used ecm ,Truck running good .have a lighting bolt code for engine brake , reckon the truck the ecm came from had engine brake. Quote Link to comment Share on other sites More sharing options...
Mack Technician Posted August 28, 2019 Share Posted August 28, 2019 (edited) Be aware RED! Don’t wreck your new ECM. What Fred is talking about is capillary bleeding through the wire. The sensor in your coolant tank ruptures internally and 10 PSI will push coolant down the wire using it as a capillary tube. That’s how coolant gets in past the seals of the J connection. Its not likely coming from outside in, but rather inside out. You can pour coolant over the outside of your ECM all day and the seals will keep it out. The capillary failure is coming straight in via the unsealed wire. Coolant flows down the wire like a pipe. Mack makes a jumper you install in the wire connection leaving the sensor. It’s a few inches long. The jumper has a sealing compound pressed into the wire strands. If the coolant sensor ruptures the coolant will hit the protective jumper and dead-head. Mack was handing out jumpers back in the day. Check to see if you have the jumper. If you don’t, install a new coolant sensor and jumper. If you do, install a new coolant sensor and jumper anyway..... cheap insurance. Edited August 28, 2019 by Mack Technician Quote Link to comment Share on other sites More sharing options...
R.E.D Posted August 29, 2019 Author Share Posted August 29, 2019 Wow.! I understand stand now.will look into it.thank you every one. Also will probably need to change the lower connector on the ecm...they are kinda corroded and were given me some pita this morning.i cleaned them out with some small picks but not real sure bout them.is it better to change cut and splice a new connector or install another harness? Quote Link to comment Share on other sites More sharing options...
Mack Technician Posted August 29, 2019 Share Posted August 29, 2019 Service bulletin SB273009 coolant level anti-capillary jumper harness. 1 Quote Link to comment Share on other sites More sharing options...
R.E.D Posted August 29, 2019 Author Share Posted August 29, 2019 41 minutes ago, Mack Technician said: Service bulletin SB273009 coolant level anti-capillary jumper harness. I unplugged the coolant sensor plug and sure enough it was full of coolant 1 Quote Link to comment Share on other sites More sharing options...
Mack Technician Posted August 29, 2019 Share Posted August 29, 2019 Nice find, disappointing it took money out of your pocket. I wonder how many trucks are running without the capillary protection? Quote Link to comment Share on other sites More sharing options...
JoeH Posted August 29, 2019 Share Posted August 29, 2019 Should have been a recall item. 1 Quote Link to comment Share on other sites More sharing options...
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