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Hey y’all brand new here and happy to be a part of the Mack truck site! Always loved big trucks and equipment since I was a little kid. First one I ever got to see close up was an old cab over freightliner that my grandparents had for their logging company when I was a little kid.Earlier this year I got hired at a local sand and gravel/ excavation company as a mechanic for everything and I love every minute of it! I’ve been wrenching all my life but I’ve never really enjoyed wrenching on anything as much as I enjoy wrenching on these old trucks and equipment, well besides classic cars and motorcycles that is. Our fleet of trucks are 2 98 cl series Macks, 2000 international 4900 tri axle, and a 99 Ken worth T800. Here is a picture of the truck I’m working on right now. It’s a cl713 with the E7-460 Mack engine. It’s randomly quitting and losing all power in the cab. I am not sure what the problem is. I’m told it could be the solenoid on the firewall next to the wiper motor IMG_0019.thumb.jpeg.3af8db5a2d3b097512828ec995f86558.jpegIMG_0020.thumb.jpeg.a9ea3906b11fd1d9d67fdbfc55775e3b.jpeg

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One if the wires on the relay on the firewall is cab power. It is on the post with 2 other wires. I assume you checked the battery cables and ends. You say the cab goes dead.. so nothing, not even the radio, horn dash lights, ect. Works? Does it have the acc. relay in the top center behind the dash panel?

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2 hours ago, Joey Mack said:

One if the wires on the relay on the firewall is cab power. It is on the post with 2 other wires. I assume you checked the battery cables and ends. You say the cab goes dead.. so nothing, not even the radio, horn dash lights, ect. Works? Does it have the acc. relay in the top center behind the dash panel?

Yes everything in the cab goes dead. Even the cig lighter when the key is on I only know that because it killed my power probe when the key way on. Even the lights on the truck and trailer weren’t functioning. I did check the battery cables and everything was kosher there as far as I could tell. I was able to put power to the battery wire picturedIMG_0021.thumb.jpeg.fcffbb35b9ea901fa0a15f3e1b5ed3bd.jpeg going to the fuse panel and the heater blower powered up and the truck would crank and fire up, but die seconds later. Idk if it was a fluke or what but my boss showed up and was able to keep the truck running by shutting the heater off and we got it back to the yard. The acc relay you’re talking about, is it behind the gauge cluster? 

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if it has the type im thinking of, its under the cup holder, behind the switch panel..  I forget when they went from that type, to the cube type in the fuse area. there may be a vertical row of them to the left of the fuse panel. 

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2 hours ago, 70mackMB said:

When does it lose power, parked or moving after hitting a bump? Follow what Joey has to say and check the cab ground also.    .....Hippy

Doesn’t matter if you’re moving or not it will just quit and lose power in the cab. This morning it was 20 degrees and I fired it up cold without the heater blower on, it died almost immediately after it was running and lost power in the cab. I jumped the starter and let the starter motor run for a second , got back in it after I snuffed her with a little ether and she fired right up and ran.

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I read this again, the heater fan thing is interesting, I know they draw a lot of amps. any chance you saw the alternator gauge when this issue happens? i'm curious if there was a major voltage drop, or even a spike..  

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1 minute ago, Joey Mack said:

I read this again, the heater fan thing is interesting, I know they draw a lot of amps. any chance you saw the alternator gauge when this issue happens? i'm curious if there was a major voltage drop, or even a spike..  

I wasn’t looking unfortunately because my boss was in the truck. I had the switch panel under the ash tray and cup holder pulled today and didn’t see any relays in there but I will look again tomorrow. I did discover another fuse panel under the hood I didn’t know about though. The solenoid on the firewall has three wires running off of one side. One goes down to the starter solenoid I think, one goes into the cab, and the other goes to the fuse panel under the hood IMG_0023.thumb.jpeg.468fcd77c27a2e3a415a39d2697a09d3.jpegIMG_0022.thumb.jpeg.b5e6fd5fb2bab0a168ead8a108003ecd.jpeg

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you are correct about the red wire routing.  just for kicks, on the black relay looking thing next to the relay....  remove the single wire and put it on the other post and re-test..  that black thing is called a ground breaker...  it's a major elec. part..  if it fails, you have what you have now. 

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On 12/11/2024 at 7:03 PM, Mark T said:

You do know it would need to be a continuous duty solenoid. Not a momentary one 

Yes I know. It was a used solenoid and ground breaker off of the same model Mack 

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9 hours ago, Joey Mack said:

I hate that I am forgetting things..  Do you have an injection pump with the electric gov. housing?  

It’s the E7-460 engine so I believe it does on the passenger side of the engine next to the eco

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On 12/13/2024 at 6:38 AM, Joey Mack said:

If so, the duetch connector is know to have the terminals loosen and break contact. Make sure to secure it to the little bracket that holds it..

I’ll check it out at work tomorrow thank you

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