Hello gents, I am in the process of purchasing a nice truck off a member here. He says he changed the o ring on the fuel filter, and next thing, the tach doesnt work, causing the trans to be in limp mode. Im guessing its a wiring issue, how can I check the wiring to rule that out? Doubt the sensor fried somehow.
tach not working
- Thread starter Greg5OH
- Start date
icanfixall
Official GMM hand model
Easy way is to replace the tach sender with a known good one if you have one laying around somewhere. Might look closely at the wires to the sender too.
icanfixall
Official GMM hand model
Sorry. I have no idea the thread size. Take out yours and see what the thread is. I believe its a fine thread machine bolt size. Maybe 3/4 inch or near that. Drive to lowes or home depot. Remove it and take it in to test fit it. It has an o ring under it to seal so its not a pipe thread thats a taper thread nor is it a straight pipe thread. if your lucky enough to find the right size and thread make sure the bolt is cut short enough to stay away from the rotating injection pump gear. Can't find an o ring for a seal just use rtv or a gasket of some sort under the plug. Why do you have to plug the one in your 5 speed if you take that with you. Is someone going to be driving it. If nobody drives it just disable the truck so it wont start and leave it be.
wildman7798
Full Access Member
Here is a link to a post from OldBull last year with all the troubleshooting and testing tips from the factory service manual.
http://www.oilburners.net/forums/showthread.php?59468-Tach-Sensor-testing
http://www.oilburners.net/forums/showthread.php?59468-Tach-Sensor-testing
The thread size is a 3/4"-10 NC bolt.
Last edited:
icanfixall
Official GMM hand model
Very well played Bill. Glad someone had the thread size and pitch. Gotta store that info somewhere.. Now what am I going to have to forget so I can remember this....
