Jump to content

Recommended Posts

I have been searching and searching for the problem on this truck  it's a 96 ch e7 454, throws blink code 4-2 I changed the speed sensor , didn't help at all. I have no tach no speedometer, but if I start truck and pull seedo circuit breaker the light goes out and stays off but I have not been able to test drive to see if it got the power back ..  only gets about 15 psi boost  and the boost needle shudders to get that . It runs fine no miss or anything just no top end power 

Link to comment
https://www.bigmacktrucks.com/topic/74143-tourqe-limit-switch/#findComment-551496
Share on other sites

45 minutes ago, dependable dirt said:

I have been searching and searching for the problem on this truck  it's a 96 ch e7 454, throws blink code 4-2 I changed the speed sensor , didn't help at all. I have no tach no speedometer, but if I start truck and pull seedo circuit breaker the light goes out and stays off but I have not been able to test drive to see if it got the power back ..  only gets about 15 psi boost  and the boost needle shudders to get that . It runs fine no miss or anything just no top end power 

I just went out and looked the only thing on top of that cylinder at the back of the trans is a air line . No sensor, is there a chance that this truck does not have a torque limit switch 

Link to comment
https://www.bigmacktrucks.com/topic/74143-tourqe-limit-switch/#findComment-551497
Share on other sites

I am not sure how to attack the speed sensor as I have traced wire up to where it meets main  harness no issues, can the 4-2 blink code cause derate.  I have dash and kick panel removed I can see most of the wiring but it is still bundled tight. I have not started cutting  all the zip tie and investigated every wire 

Link to comment
https://www.bigmacktrucks.com/topic/74143-tourqe-limit-switch/#findComment-551498
Share on other sites

Do you have a duetch plug on the back of the injection pump? Another way to tell, is when you turn the engine off, does all of the dash power turn of instantly, or is there a 7 second delay?

  • Like 1
Link to comment
https://www.bigmacktrucks.com/topic/74143-tourqe-limit-switch/#findComment-551690
Share on other sites

https://photos.app.goo.gl/AHKrmPRucm8eYgVj8...  I have dia grams in my shop but cant get to them right now..  they are large Mack printings.  However, you should be able to use the info I posted to find the wire(s)..  Jojo

Link to comment
https://www.bigmacktrucks.com/topic/74143-tourqe-limit-switch/#findComment-551706
Share on other sites

Thank you.  I didn't see much on the speed sensor.  I couldn't find a tourque limit switch on this truck so I am leaning to 4-2 code being culprit, I have no tach and no speedometer working on dash.  I replaced speed sensor and it did not work . So I am hunting for a wire short with the speed sensor I checked the back of dash cluster not visible issues there 

Link to comment
https://www.bigmacktrucks.com/topic/74143-tourqe-limit-switch/#findComment-551707
Share on other sites

remove the speed sensor and see if its cracked. when you put it back in, go all the way in lightly touching the tone ring, then back it out 1 full turn.  ohm the sensor and post the reading. I will check it in the book, im busy, so I may be slow to respond..  

Link to comment
https://www.bigmacktrucks.com/topic/74143-tourqe-limit-switch/#findComment-551708
Share on other sites

FJH, i dont have simple diagrams, i have the big fold out ones that you get from Mack Schools. Im hoping the info i posted from my V-Mac 1 book will get him what he needs

  • Like 1
Link to comment
https://www.bigmacktrucks.com/topic/74143-tourqe-limit-switch/#findComment-551740
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.

  • Recently Browsing   0 members

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