Jump to content

RD Intermittent power loss


Recommended Posts

New to the form any help is appreciated. I have an 02 RD 688 with the 460. When i bought the truck it had the problem and i have chased it since. You will be going along and the tack will go to zero for a few seconds engine dies and then restarts. The local mack garage changed both speed sensors and over the winter i sent the ECM out thinking it that it might be that. I drove the truck yesterday and it still has the cut out. 

 

Other issues

When you go to shut the truck off sometimes you have to turn the key back and forth a couple times before it shuts down. I have checked the wiring and replaced the key switch hoping to fix the issue with no success. Not sure if the 2 are related or not but any thoughts on this issue is appreciated.

When you plug into the truck it had/has a code for the pyrometer. But there isn't an engine light on the dash. Mack said the bulb was missing but i pulled the dash and its a sealed unit 

Link to comment
Share on other sites

If you're engine light is working it will power on for a few seconds then go out, assuming there's no active fault. Should look like a lightning bolt.

You should have two fuse boxes, one in the glove box the other under the hood. Fire up the truck, look for the fuse that says EECU, wiggle it. I bet your engine will shut down. You'll need to pull that fuse/circuit breaker and squeeze the terminals a little tighter so they get a better grip.

  • Like 1
Link to comment
Share on other sites

in the box under the hood is the fuse for the ecm.  #40 or 41... typically in the middle of the middle row. there is also an accessory relay next to the fuse panel in the cab, it looks like a black square cube, I dont remember the # of the socket..  when you say speed sensor's, do you mean the crankshaft and the cam sensor's?  jojo

Link to comment
Share on other sites

Engine position sensor is a cam sensor, Engine speed sensor is at the flywheel housing, and vehicle speed sensor is at a tone ring on the output shaft of the trans. 

  • Like 1
  • Thanks 1
Link to comment
Share on other sites

the fluctuation at idle,  may be the fuel pressure regulator..  I cant tell if one was installed,  also did you have a 3-2 or 3-4 code? jojo

Link to comment
Share on other sites

Also for the running “ok” and idle surge have someone check the fuel pressure. Was common for the etechs to have the plastic gear in the fuel pump strip and spin on the shaft. Also fuel pressure regulator like Joey said. 

Link to comment
Share on other sites

Would be nice to see what codes are in this. May have a J1939 issue. I know when J1939 is lost, the truck will not shut of immediately and will take 5 seconds to shut down.  Never had a TPS cause an idle surge when the engine is cold. Usually if the tps is lost, the engine will default to 900rpm. The fuel system should not be checked at idle only, this should have been road tested under load with a manual gauge in the fuel system and then readings taken. That would have given you a more accurate reading. We really don't know if the fuel system is at fault still.

Check to see if there is a rectangular connector on the driver side on top of the transmission, if it does run the truck and wiggle that connector and see if you notice a change in the engine. If it does then pull that connector apart, clean it with contact cleaner and put a zip tie around it nice and tight. 

Let us know what you find.

V

 

  • Like 2
Link to comment
Share on other sites

I checked the ECU fuse and wiggled per Joe H with no luck of killing the engine. See below in the video with no engine light coming on. 
 

The idle surge is no longer as issue but thanks for all the input it just needed a set of filters. 
 

The big problem is the truck dying out while driving and then coming back to life. 
 

Since to lighting bolt isn’t currently available I don’t have another way to check codes do I ? 

V Mac3 I don’t seem to find this connector any other descriptors ? 

 

Link to comment
Share on other sites

That connector V is talking about is on top of the bell housing. You may be able to sneak your hand up there. If not take the passenger side floor out. 

Link to comment
Share on other sites

On 3/21/2022 at 12:14 PM, HarryBiron093 said:

New to the form any help is appreciated. I have an 02 RD 688 with the 460. When i bought the truck it had the problem and i have chased it since. You will be going along and the tack will go to zero for a few seconds engine dies and then restarts. The local mack garage changed both speed sensors and over the winter i sent the ECM out thinking it that it might be that. I drove the truck yesterday and it still has the cut out. 

 

Other issues

When you go to shut the truck off sometimes you have to turn the key back and forth a couple times before it shuts down. I have checked the wiring and replaced the key switch hoping to fix the issue with no success. Not sure if the 2 are related or not but any thoughts on this issue is appreciated.

When you plug into the truck it had/has a code for the pyrometer. But there isn't an engine light on the dash. Mack said the bulb was missing but i pulled the dash and its a sealed unit 

Does the new key switch still need a couple key cycles to get it to shut down sometimes? That seems strange, possible short circuiting in a wire harness?

Link to comment
Share on other sites

good call JoeH... I also thought the accessory relay was sticking,  but you have a good 'Q'  jojo

Link to comment
Share on other sites

so here is two different pics of that plug at different angles. It’s got a metal bracket around it and is mounted on top of the trans by one of the bellhousing bolts. Did you happen to have any work/transmission work done to this truck before this problem started? 
image.thumb.png.7cff5d64264e3db646e2ee87fab1888f.png
 

image.thumb.png.b68764347c7f548f135513a388ad7f19.png

Edited by Onyx610
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...