Richardsmack

Will try an extra ground. Thanks. Will post when It works or if I find a solution.

It's the 6 pin connector. E tech engine yes. e7-350. Everything was working until water came into the vecu. Replaced it with a used onne with same #'s.

Thanks Joey. Those wires I connected to 2 new temporary wires to the ecu as a test. No difference.. So I put everything back like it was. I'm thinking to buy the nexio usb link 2 with the 6 pin cable. What I saw is that the v-mac software is free Version 2.9.2. Only problem would be to get the proper config files for my vin#?

Still having the 6-4 code. Trucks is in limp mode. I went to the dealer 2.5 hr drive one way. After they installed the software on the laptop and with help from mack support (3 hours later) they were able to read the ecu and the vecu. In the ecu was a different vin# and it read e7-460.... I think they updated the vecu with this vin#. Not sure as I was not there all the time. The problem stayed the same. Even though I measured all the connections and wires they decide to do that again. No luck. 7 hours later. The mechanic was afraid to program the ecu with my own vin# because he was afraid the truck would not run anymore after the update. So now I'm really stuck.... Would it be a 460? or just the ecu from a 460? I'm almost sure it's a 350 as the truck came with that engine and it shows on the valve cover. I'm out of options. If a mack dealer can't fix stuff... It would be nice if I could send the ecu and the vecu to someone who knows what he's doing. If you have any ideas please let me know. Thanks for your help.

Checked connections and they're ok. So I think the software versions are different between the old and the new VECU. However I keeps on running when driving. Have to do some other work before the inspection and then it needs to be hooked up to a computer to verify the programming....

Pffff. Had it idling for a while then it shut itself off. Started it the after 10 min it did shut off again. Engine code bulb did not work. Now it does. Fault code 6-4 which is J-1939 link which is communication between de VECU en computer aside of the engine. So now I have to check connections again.... Man I hate electronics.

Made a MacGyver plastic cover :-)

Put in the new/used vecu from a CH with the same part#: It started right up Yeee Haaaa. Thanks everyone for your help.

Thanks :-) At least all the wiring is looked over and everything is clean now. Once I find the new/used V.E.C.U I'm going fabricate a plastic cover so that it can't happen anymore. It has been a good learning curve as well. Will let you know when the box is in and if it works. Thanks!

Well as kinda expected the unit is fried. It works a bit better though. So now I have to find the module for a reasonable price.

Day #4..... Was reading the truck manual and it pointed to a circuit electrical box behind a panel under dash passenger side. Opened the panel up and discovered the box and disconnected it. Water came out...... Drying and cleaning it now. Hopefully it still works. If not I have to look for another box. Let's hope for the best. While drying I have to see where water comes into the cab. I'm getting somewhere :-) Will let you know. Thanks !

Maybe I fried the ecu.....

Today I cleaned all the grounds. Cleaned battery terminals and connection cables. Disconnected ecu and tried the ignition no difference. Cleaned the fuses and checked them. Disconnected the alternator and tried. The power stays on if the ignition is off. When starting it turns the starter when let go of the key everything shuts off proper. I noticed that when turning the key in the on position I don't see the orange engine fault lighting up anymore. checked and changed that bulb. Anyways I'm out of options. When I take every relay out everything is out/off except for the parking brake light. When I put the relays in everything has power still with ignition off..... Time for a beer. So it keeps the power on but I cannot find another relay which might be sticking............................. I'm out of ideas.

It must be a ground problem. Again when I put the ignition on on everything goes on. When I turn the ignition off power stays on as whenever i pull a relay and put it back it clicks plus the heather blower stays on and fuel gauge and both have nothing to do with the ecu. But then when you crank the engine it starts but shuts down right away and then everything shuts off. Sorry for repeating :-) it does not make sense to me grrrr. Will post when I make progress. Thanks for the help !

Cleaned the contacts on the 50A breaker and checked with multimeter(black box). Same with the starter relay. Just in case bought a new ignition switch and connected. I can't find the acc relay. All I can find see picture. The one hanging loose in front of the fuse panel is for daylight running lights (now disconnected). The other one loose see first picture is I think acc relay which I swapped. Tomorrow when the sh... rain is gone I will clean all the grounds on the frame.

Thanks for the advice/hints. V-mac III. I will let you know once I cleaned the grounds etc. That lawn tractor starter relay(acc) is not to find inside the cab. Only one is on the picture which should be the starter relay... Meantime checked fuse box middle firewall. relays were corroded cleaned everything. Again thanks. Ttyl.

Thanks Jojo. Before when I shut it off after the delay of 5-7 seconds I heard a click.(what clicks?) Now it doesn't as the power stays on I guess. I measured trough the switch and it should be good but maybe under power it's not... But then I used a wire in the plug to bat -- ign same thing powers up and when disconnecting the wire everything stays on... I swapped the relay under the ashtray as well. Now I have to find a switch. Possible a universal one which I have to rewire to the cluster.

Hi All, It's been a while but I still have my 1998 RD688 E7 350. Yesterday I came across a strange problem with my dash electronics and starting the truck. Today again I broke my head figuring it out. Mybe you can help me in the right direction to fix it..... So yesterday I charged the batteries (one by one disconnected from the truck) as it was sitting over the winter. When I tried to start it it would run for a second and then die. I noticed the dash power to the fuel gauge, parking brake light, and heater blower stayed on while the key was in the off position. Tested the switch which was fine. Just in case I used a wire instead of the ignition switch.. same thing If I put the switch on contact the fuel gauge etc go on. When I put the switch in the off position power stays. Looked at the relays. they work fine. I took them out when the ignition was off but still had power as by pushing in the relays back in the fuse box I could hear click. Now when you actually turn the key further to start it it will fire but then dies and when the key is put in the off position the everything goes off like it should. I checked for ground issues etc but could not find anything. One thing is I'm not sure of see picture. Black box under starter relay with the little screw in the middle. Whenever I turned the truck off the gauges etc would stay on for a second or 4 and then turn off. Would it be the black box? What is it? (i found it it's a circuit breaker 105 amp) Thanks for your help 🙂

Thanks! I will do that and see if that makes any difference.

Hi Terry thanks for your reply. I have the original factory print out and it says 14.300. Meantime the check engine light came on and went off. Code #3 injector electrical issue. Cleaned the contacts/wiring. Maybe this has something to do with the blue smoke while using the engine brake. When driving no blue smoke except when it idled for a bit and then taking off. Any ideas? Thanks!

More than a year later.. Love my Mack !!! I custom fit a new front bumper and sanded and painted the truck. Coolant problems are over as I keep the overflow bottom canister empty. It runs awesome except for smoking puffs of blue smoke when using the engine brake.. Anybody knows what could cause this? I'm also still looking for a 20.000 lbs front axle. Would an axle from another brand truck fit? Thanks for your input. (Current job 2 weeks into the mountains up and down a 10-15 mile logging road. Hope my baby survives this.) 🙂

The last couple of Months I drove the truck a lot. In September 3 weeks 7 days a week 12 Hours a day ! It did throw out a bit of coolant out of the overflow but that was it. No oil leaks out of the breather and in all that time it used approx. 3 quartz of oil. Love the truck and it's very good on fuel.

Thanks for your help ! Yes I run it now with the overflow tank with a little bit of coolant in it. Regarding the oil splash when on a very steep grade that makes sense. Below a couple of pictures of the start of making the truck look nice. I'm still looking for interior parts and in the future I like to get a heavy duty front axle. Hard to find parts here in BC. Next is fabricating a beefy front bumper. I will let you know how the truck is behaving. Again thanks !

Hi All, I have 2 weird problems with my Mack. I recently bought it and I'm in the progress to fix it up. I replaced the 2 fuel filters, 3 new oil filters and coolant filter and new engine oil. The engine runs good without any white or black smoke. When I bought it the coolant overflow tank was empty. I thought nothing of it. Later I filled the overflow tank (bottom) till the mark. The top one was full. After a drive I noticed that coolant was pushed out the overflow tank. I checked for bubbles..nothing. replaced the radiator cap. No leaks anywhere. When I use it without the overflow tank filled everything stay good and not running hot or so. Also the top tank stays filled... Any Ideas ? Problem 2: I was hauling last week going up steep mountain roads and going down and delivered the materials to the a owners property with a very steep driveway going down and it was only possible to drive down forward. My truck was spitting quite a bit of oil out of the breather tube. When I noticed that I stopped that afternoon. I checked the oil when parked level and you could notice the oil out. Once home I she sat overnight. Rechecked the oil and added like 2 quarts. The I drove it 2 days in a row on the flats. No leaks out of the breather tube just a bit of smoke/fumes. The I did the last day hauling same route and steep driveway. Lost oil again. Just used it for the day and added oil later. Other than that the truck runs like a dream no smoke and very good on fuel. Any Idea's ? Thanks for your help. By the way the other 4 NON Mack trucks all fell apart mostly suspension :-)