'78 with wiper trouble

[Scott M]

Ok I would like to ask a few questions about my wipers...

1st off 78 truck with 3 postion switch on dash (Off/Low/High)

When the truck was parked 1 yr ago the wipers worked fine no issues
 since then have replaced the engine in the truck now its time to get it ready for inspection and the wipers did not work.  I have not mess with internal wiring at all and did not mess with the wiring in the engine compartment that pertains to this thing. 

First i decided to replace the switch since it is cheaper than the motor. so i did and they came on! but when trying to turn off they would not park or turn off.  I then procedeed to take the switch back out and when the metal tabs are not touching the metal on the dash they work normal as then should.

then with the key on engine off and the switch to off i put it back in and screw it in again and they stay off.  then if i move the switch they stay on until i either turn the key off or unscrew it from the dash.  also the switch is very very sensitive when it is touching the dash. not senesitive at all when not touching.  I have looked at wiring and can not determine a problem.  research has told me that the switch is grounded through the dash and the metal tabs...if this is correct then the opposite sounds true to me, they should not work at all with the tabs and switch not grounded to the dash and should work normal when grounded to dash and the current is allowed to flow the switch in a closed loop as it should.  this is why im wondering if it could be a bad switch i bought from oriellys and the other main reason is it worked perfectly fine before

any help would be awesome

[zieg85]

I wonder when you changed the engine you messed with the ground.  Did you put the ground wire back from the head to firewall? 

[Scott M]

I will check when i get back looking in the engine compartment, i know its very possible that i did not, i will update with pictures and and list the grounds that i do have, another thing i just thought of is the dash lights are not working when they did work before could be another sign of a bad ground! Ill update tomorrow night

[Scott M]

I have looked on the forum and found the electrical diagram for my truck but I am having a hard time figuring out where the ground hooks on the cab... If anyone could post a pic of where they have their ground going then that would be awesome! I have a new ground strap purchased just need to know where it goes to get the ground I need.

I know that a ground is probably just a ground and i could make a new one but I would like to hook it upo to where it was before...

I am hoping this solves my wiper issue and also the guage issue...The fuel guage does not work along with all the lights on the dash.... I do have aftermarket guages wired up and they work fine...the wires are ran from the fuse block to the guages and the ground is to the ground block that comes stock and they work normal so it does not make complete sense to me but i guess it would explain why they worked before and not working now because I do not have a engine to cab ground....I looked I just have the engine to frame ground on the front....

[enaberif]

Driver or passenger head has a 3/8 bolt hole. Get a ground strap and secure it from here to the body somewhere. I attached it to this bracket..

[Scott M]

THANKS! I appreciate it! Im going to do it this afternoon! thanks for the pic, Ill update to let everyone know if this fixed the issues!!

thank you enaberif

[blazer74]

Also possible the park switch in the motor is bad.


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[Scott M]

Ok so this past friday i went out to the truck and installed a ground strap from the back of the drivers head and connexted it to the cab at the same point mentioned above while leaning back there another electrical cable had broke on me i went to see if the ground worked for the dash guages and nothing worked then sat morning i figured out that this broke cable was to the battery junction block. I could not source an original replacement in town at the auto parts store so i bought a universal block and installed it. BAM power was back i then installed the switch with the screws and my wiper problem was solved had to be the ground! Thanks for all the help!

I then checked the guages and i had nothing so then i started taking the cluster out just to see if anything looked funky or disconnected i took it out to find that the harness was not even plugged in!!! Dang! Plugged it in and BAM guages worked!

Only thing not working now regarding all this is the lights to all the guage lights wont light up and i checked to make sure dimmer was not all the way down and it wasnt....my question is, if one bulb is out will that cause a break in that electrical plastic circuit thing? Easiest way to check this thereoy would just check them but i installed it back up and just havnt gotten around to taking it all back apart....

[bd]

...I figured out that this broke cable was to the battery junction block. I could not source an original replacement in town at the auto parts store so i bought a universal block and installed it.

Did you replace the junction block or the 6" long, 16-gauge fusible link?  The location and size of that link is crucial to protecting the truck from electrically caused fire.

...my question is, if one bulb is out will that cause a break in that electrical plastic circuit thing?....

No.

Check/replace the 4-amp "Panel Lights" fuse in the fuse box.  The Panel Lights fuse is electrically located between the instrument lamp dimmer rheostat and the dash lamps.  The Panel Lights fuse is redundant and secondary to the "Tail Lamps - Courtesy" fuse.  For more information, see "Diagnosing dash lights that don't work" in the Technical Pages.

[Scott M]

Did you replace the junction block or the 6" long, 16-gauge fusible link?  The location and size of that link is crucial to protecting the truck from electrically caused fire.

I Looked on the Internet and it is called a junction block here is a pic of what I replaced please tell me if this is wrong.  The wire that broke at the connector went to this block, I had to replace the whole block because the nut was rusted on the post an the whole post turned trying to back the nut off. I plan on getting an original ordered today...

and thanks for the information i am going to check the fuse today after work....

[Scott M]

I only cut the wire at the end on the connector part that attaches to the post. there was like a 2" looked like enclosed link that was a little further down the wire I left that in the wire im not sure if this is what you are talking about....

[enaberif]

Fusible links are fatter than normal wire because of the encasing. If you took a pic of the current setup we can help you more.

[Scott M]

Fusible links are fatter than normal wire because of the encasing. If you took a pic of the current setup we can help you more.

Ok I will get a pic of the set up I have now and also of this wire... I believe that the previous owner had the wiring to the junction block wrong.  there was two wires going to the same post and none going to the other post.  you will see the current set up I have it has one wire going to one side of the junction block and the other to the other side or post of the aftermarket junction block.  I assume with the two wire on the same post that that would potentially cause an electrical problem because it would essentially be like splicing the two wires together and not even running the junction block if they were tied to the same post. my current set up that i installed (pics to follow) seems to be the right way in my mind lol