Wiper electrical issue... finally stumped

[DPF_free]

Hey guys, any of you guys in the Denver area know we have been having some insanely bipolar weather lately... anyway the last wet snow we had I turned on my wipers and they couldn’t push the snow off so they got stopped, and a guy a work with distracted me so I left them on and stuck at full speed. After I cleared the snow my intermittent modes, park and wipe after wash don’t function, however high and low speed do. I was sure I cooked the contacts in the relay so I switched it with another one showing the same diagram and nothing changed... I did some digging in the forums and was led to the CTM, but the other morning I was sitting outside the job with the truck off and had the MFS on the shortest intermittent setting (since that is now “off” and easiest to make a manual intermit) and could hear the relay cycle, I tried all intermittent settings and the time between the cycle changed, so in my mind the CTM and relay are doing their job just fine.

It is my understanding from the FSM that the CTM sees a signal from the MFS then sets the interval for the time to turn on the low speed brush of the motor and then the end switch lets the cycle comple back to parked... I have not been able to check the end switch function yet but I believe it will be the problem... has anyone else seen this problem, if so please let me know if I’m on the right track and if there is a simpler test I have missed rather than looking for voltage/ continuity between the end switch and whatever wire on the CTM as the manual suggests.... thanks in advance

 

[PBJ2500CTD]

DPF_free,

Your symptoms indicate the park circuit is not functioning properly. I assume the washer nozzles are spritzing juice when pushing the switch, just no action of the wipers happening. Anyway, check the 25 amp fuse (#6) in the fuse block. This fuse supplies power to the wiper circuit in the intermittent and park modes of operation, which are the modes you are experiencing issues with. If no issue there I would look at the motor assembly park switch.

 

[BK]

Usually when you fight the snow with the wiper blades, the contacts and pads that are built into the module with the wiper motor burn up due to the excessive current.
So you loose the park sensing and feedback for the other functions of the wiper delays.

One then needs to replace the motor assembly under the front window valance.
Not too hard to do.
Hardest part is getting the wiper arms off.
While your at it, must buy new wiper arms.
Ask me how I know.....

 

[BK]

www.amazon.com/gp/product/B000CFHDO4/

Not sure of your year truck, but I bought this for my 99, perfect.

 

[Joe Mc]

For the past few years I had a similar problem, intermittent wipers would work "but" sometimes they would stall about ¾ of the way up and then in the same spot as they returned to the park position. A new wiper motor fixed it.