In cab wiring please help me fix this new nightmare

[94extcabf250diesel]

ok guys now that the truck runs great i also noticed the tach dont work proprly it says liek 50rpm when idling and well idk the tach just asks funky and i know its not a true reading. also whenever i hit anyothr electronics like turn the light switch on for parkign or headlights all the guages in insturment cluster go nuts. Also i noticed i have 2 1100 cranking amp batteries and well it always seems liek the batterys are always low i check them on charger and they seem good. I noticed the ground wires to the batterys aren't to great at all so im goign to change the grounds. Also i noticed when puttign the parking lights on or the headlights headlights and parking lights in the front dont work. I know the parking lights work on the bed when i pull the switch on.
thanks,
jimmy

[Phillipmc1268]

1. Remove the instrument cluster, clean the contacts where it plugs in.

2. Starter may be in bad shape from extended cranking.

3. Check the bulbs first, then get after it with a test light. The light switches are known to be unreliable.

[suv7734]

Until you get good grounds you won't be able to isolate anything. You indicated the battery side looks bad but check the two connections at the block as well. Poor grounds will drive you crazy. Once you get the ground issue out of the picture you'll probably find there are fewer problems than there appear to be. Have a smell near the headlight switch, they have a tendency to burn up the harness and you'll be able to smell it if it's starting to go.

[91diesel]

Think about replacing the tach sender. You can test but i dont know exact procedure, QUE CDNSARGUY. The sender is the big 1 inch nut on the ip gear housing. It has two wires coming out of it. I believe last time i checked it was a pretty cheap part and wasnt recommended to test and keep.

[94extcabf250diesel]

yeah it looks liek on the one battery ground wire it looks liek somoen took it and stripped about 6inch logn section of the coatign then untwisted it and cut 1/2 of the wire so only half of the wire is still there actually making a ground. the other side dont look nearly as bad but im going to change both of them. then starter i think if fine because i think its mainly the grounds to the batterys (expecialy the one side i mentioned about) makign it hard to start. after the truck is runnning it seems like as soon as you try to use juice somewhere else it takes it away from the guages and makes them quit working or work improperly...

jimmy

[cdnsarguy]

A dead tach sender should/would send the automatic trans into a "failure management mode" (limp mode) with harsh engagements and firm shift feel and an abnormal shift schedule. It has no effect on a manual trans only the Tach readings.

Check the wires where they exit the big nut on the oil filler housing, known to short out due to bare wire.....

Replace the tach sender on the oil fill housing a big 1" nut with 2 wires. Ford only part Engine RPM sensor E5TZ-17B384-A about $50. You can remove and clean it but usually changed later too.

You can test it too, hold it in the air away from ferrous metal, using an ohm meter lead on each wire you need DC resistance between 2000-3000 ohms.

[88beast]

wow must be a fasctory fix mine is the same way about 6 in stripped off and twisted sround a bolt i plan to fix it when i can but that may explain the lack of reverselights the tach and fuel gauge not working and all the other problems