I have intermediate problem with both green M&S mode dash lights indicating a problem. Sometimes if I stop engine and restart they go off for a period but usually come back after a period. There seems to be a slight loss of power when they are on. Any ideas would be greatly appreciated.

 

That's often due to a low battery. Check the terminals and clean the ground connections. Also have your battery load tested and check the alternator output to make sure that is all working well.

 

Thanks for that Mollusc I'll get it checked but in the meantime and in your opinion is it causing any damage ?

 

Shouldn't create any other problems. Despite cranking seemingly fine and the truck having no other battery issues, they are sensitive to low voltage. If my 04 sits for more than two weeks I'll get the flashing M&S upon restart. A quick fix is to put a battery charger on it for a couple hours and see how long the lights stay off. If they're back the next day you likely need a new battery. As mollusc says, you should check alternator output first. if you have a meter, probe the two battery terminals while the truck is running and you should see north of 14v which would indicate that your alternator is doing its job. If it's low 13s or below, your battery may be fine and you'd need to replace you alternator. If you don't have a meter then run the truck down to the auto parts store where they can test the alternator and load test the battery. You will not harm the truck driving it like that in the short term however you'll notice that gearing will be affected.

 

Appreciate your input Ahab

 

You'll be in "limp home mode," so the vehicle will not shift out of 3rd gear even if you move the lever. I wouldn't treat it as a regular driver in that state.

 

Big vacuum leaks will do it too check all your vacuum lines and the hoses from the air box to throttle body