Hey everyone I'm new to this site and was needing some help. I've got a 91 f150 xlt lariat with the 5.0 e4od transmission with a little over 104k on it. The trucks a half ton with an 8" suspension and 4" body lift. Has 16/38.5-15 TSL super swampers. I just changed the spark plugs wires distributor cap rotor and fuel filter and the truck ran better than before. I swapped out the rear taillight bulbs( running, brake, reverse) and front turn signal/marker bulbs with LED bulbs and now my taillights come on when i turn my key to the run position and stay on after ive started the truck. After doing these changes my check engine light comes on after the truck has warmed up and I'm driving down the road, my rear abs light comes on around 45, it won't shift into OD but the transmission doesn't shift hard or leak and the fluid looks brand new. None of these issues came up until I made these changes. I've cleaned and used dielectric grease on the rear abs plug on the rear end and both plugs on the transmission. The transmission will shift hard into reverse only if I don't have the brake pressed almost through the floor board. Any advice from anyone will help out tremendously. I've been on here reading forums left and right and using all the similar issues to help fix my own so please don't hesitate to give me your own thoughts and ideas. I don't get butt hurt and I'm open to everyones input. Thanks in advanced

 

I suspect your problem is related to the LED bulbs you installed.

https://www.google.com/search?q=tran...utf-8&oe=utf-8

 

Sweet, I was about to install some LED load equalizer so I can have my turn signals back. I'll follow up on how the tranny starts shifting afterwards