Electrical Help Needed-Wipers

[mo-mon]

'88 Carrera. Tried searching to no avail.

When I turn the wipers on using the switch, there is voltage fluctuation (lights dim, pressure gauge jumps) but it works on all 3 speeds. In contrast, if I use the intermittent switch, all is well. Is this a ground problem or something else? I have cleaned the ground near the battery, checked the connections on the wiper motor, took out & examined the switch itself & everything looks okay.

Here is the video.

[mo-mon]

Apologies for bumping my thread but would really appreciate it if anyone could help me with this problem. I was hoping electrical experts like timmy could tell me what could cause this. I'd prefer to address this myself rather than going to a shop. Thanks in advance.

[timmy2]

My initial guess would be the wiper motor relay may have an internal problem.
Uses different contacts for normal operation and intermittent control.

[mo-mon]

Thanks for the reply, timmy2. Will pull out the intermittent relay & investigate.