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EWB555

Porch Pup
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    54
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About EWB555

  • Rank
    Old Iron Expert

Profile Information

  • Gender
    Male
  • Location
    MD

Previous Fields

  • Make
    Mack
  • Model
    RD688S
  • Year
    1995

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  1. Problem solved. Must have missed a fuse when checking. After spending the day yesterday troubleshooting from a schematic that I was told was my trucks, (it became apparent that it was similar, but not the same as mine as I was troubleshooting) I was able to pull the fuse box info from this site for a 96 Mack. Checked my truck today, fuse 16 for turn signals blown, replaced, left turn worked fine, right turn. 3 blinks then pop, blew fuse. Unplugged front end harness from near passengers side firewall, replaced fuse same result, (ok short is not in front harness). Plugged back in, replaced fuse, hooked up new turn signal switch, left turn ok, right turn -good to go. Short must have been in the signal stat all along. Shame on me for missing the blown fuse the first time!
  2. My truck is a 95, fuse 16 is for turn signals. not sure what problem you are Having, I had a short that blew the fuse, ended up being the turn signal switch.
  3. Currently have no directionals front or rear, and no brake lights. Checked fuses all good, plugged in brand new turn signal switch, no change. Tested in fuse box, no hot to the flasher. Schematic shows fuse feeds the flasher which feeds the circuit,Could my panel be shot? Appreciate any ideas. It's odd to loose both at once.
  4. Took the truck for MD inspection today...In the last few weeks we replaced the flex under the cab, put a muffler on it (it had a straight pipe) changed the front and drop axle tires, fixed the air leaks (2 fittings) Outside of inspection items I wired it for an electric salt spreader, installed plow lights, strobes on the rear of the dump bed, beacon light, our welder set it up to hang the spreader on the back, made a box to mount the plow pump on the frame, and installed a steal bumper to hold the plow frame. Also ran a new CB coax through the dash/door and put to the mirror bracket. Oh, and apparently NY spec keeps the drop axle switch on the outside of the truck?! Had to relocate the switch to the dash. It’s a steerable axle however need to control it from in the cab. After all that inspection found left turn signal on the driver side under the cab not working (dad says it was when he checked) they say it has a crack in the windshield which baffles me because I had my head all up in the dash taking it apart to run the CB coax, and the kicker- they say the manifold is leaking on the back cylinder. I have not seen it but dad says it’s extremely minor. I did note how far back into the cab this engine sits compared to our RD. Does anyone have thoughts on how bad of a job it is to change manifold gaskets on an early MP7? Appreciate any info!
  5. My dad and I picked up a 2007 Granite MP7 405 Tri Axle dump from auction this week. Truck only has 112k & 6xxx hours. Cab& chassis are in great shape, ox steel body is beat to hell. Curious on everyone's thoughts about the early MP7 engines? What do we need to be aware of? Truck sounds and runs good. Only issues I can find are a minor air leak under cab, and the small gauges on the dash are broken off from the bezel and have fallen back a little. It has the Mack 10 speed trans. So far pretty happy with it from what we see. We have owned 3 R models over the years 78,86.& 95 (still have the 95) and they have consistently been the most reliable trucks. Hopefully this Granite will live up to the Mack reputation.
  6. Been a while since I posted this. Call me crazy but as soon as temperatures went up during spring & summer this air leak went away. Now here we are in December and it's back again, I replaced the switch today and that was not the problem. I moved the switch on the shifter and that did I not seem to change the air bleed from the dash. The only thing I did realize is that when I switch to low, the leak doesn't go away, it moves to a union in the air line down under the cab. Isnt the inversion valve what steps down the air pressure? Maybe it's letting too much air to my dash switch.
  7. Figured it out. Should have known that when I cracked the fuel line at the pump and some fuel dribbled out that didn't necessary mean it was getting fuel to the pump. First thing I did today was pull the filters, neither one was full. Put 2 new ones on full of fuel, hit the primer on the new transfer pump until it was hard to pump, and it fired up after about 5 seconds. Let idle hoping that maybe it actually was the transfer pump and it just needed a good prime, but I had a feeling that wasn't it. Anyway after a few min I could tell the idle had changed and it was clearly not right, hopped in the cab gave it some fuel to confirm it was missing then shut it off. Disconnected the main line from the primary fuel filter, slid under the truck and stared tracing it, when I got to the back of the trans where it crosses over I discovered that it had a hole in it from rubbing on something. Pulled the line off the truck and will have a new one made tomorrow. Thankful it's not an electrical gremlin however frustrated that I didn't pull the filters when I first checked the truck out last week.
  8. Well, we know it's not the fuel transfer pump. Dad talked to a mechanic who suggested we try that, he picked one up and put it on today, nothing changed. I am going to mess with it Sunday, it's going to rain here all day Saturday. We didn't want to put the truck in our shop since it's loaded. Will definitely crack one of 6 lines on the pump and see what we have. From there I'm going to start checking wires in the harness. Does anyone know how to check the sensor in the side of the pump or the one in the flywheel housing? Will these make it not run if they fail? I have a multimeter and can check voltage, resistance etc. Just not sure what I need to look for. I do appreciate everyone who has chimed in with suggestions!
  9. Ok, so this evening I checked every single fuse, circuit breaker and relay, all good. No malfunction light on. Voltage was 12.5 in the fuse panel. Turned key on and had 12+ on on one pin at the round fuel pump connector, and an even 3 volts on another. Looked in both tanks, pickup tubes seem in tact, cracked fuel line at the pump and there is fuel. Thinking it has to be something with ecm or pump electronics. When cranking it doesn’t even try to start, shoot it with either and it will run a few seconds. Not sure where to go from here, appreciate any suggestions.
  10. 1995 RD688S E7-400. Shut off today, while driving. Seems to be a fuel problem as it will start and run on either. All accessories are coming on when turning key so ecm should be getting power. Thoughts on what to start with to trouble shoot? This engine is computer control but not an etec. Appreciate any suggestions!
  11. Looking at a 2012 Granite Tri Axle Dump MP7 405 10 speed, air ride. Thoughts on this model year? What should I look for? Truck has been fleet maintained 250k miles.
  12. I have a 95 RD688s with the 12 speed air shift. The extended range switch on the dash bleeds air when it's in direct. It's so bad we switch it into low in the am to allow it to air up. Everything works fine, I'm just wondering how to I determine if it's the switch or something causing air to bleed back? It is not leaking from the lines to the switch, its coming from the exhaust ports. I appreciate any suggestions.
  13. On the grant swap out the stock mike if you still have it. There is a pin in the mike plug that has a "receive"wire if that wire is off the terminal or cut somewhere in the mike cord you will get no sound from the speaker.
  14. I have a 95 rd with a 12 spd. The outside inversion valve is constantly leaking air from the botom of the valve, not from an air line or fitting(two bolted together on side of tranny, one closest to frame leaks)I replaced it and still acts the same. The only way to make it stop is if I flip the switch on the dash for low low, then i flip the switch back and the air leak is gone but will come back after driving.The transmission works fine, anyone have any ideas what's causing the air leak?
  15. My truck leaks air when its not in the off position, and I cannot get air to blow out of my defrost when selected, however the Compressor does come on. If I change the "Mulit Position Air Switch" will my defrosters work? I do snow removal with this truck and it sucks to have no defrost!
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