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1999 Suburban K1500 LT 5.7 completely stock - rebuilt engine
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Discussion Starter · #1 ·
99 Suburban K1500 LT 5.7l
Trying to debug this issue. I disconnected the 3 pin connector between the fuel pump and I guess the motor module and probed across 2 of the 3pins (it seems only 2 of the pins are used). When i activate the steering column switches, the wipers move fine, but I only get a small fluctuating momentary voltage on the pump lines, down around 0.10 volts, very noisy. I am expecting 12 v here. I was thinking it must be the motor module and swapped that out but nothing changed.

What am I missing here? Is it a line short?? The wiring routing here is a pain...any thoughts to debug this?
 

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I have fixed 2 wiper module boards simply by resoldering every single component because they were cold soldered when manufactured. That is when you get a board with molten solder on it and quickly throw in all the components and never actually solder them properly. Some components can be pulled right out as a result of this method. The problem is usually with the plug connection on the board specifically though. One board I needed to add a jumper because part of the circuitry corroded and fell off.

I dont know anything else about this system though. Never checked any voltages or messed with the multifunction switch, gee I dont think that would be fun. The cold solder problem is well known....

Al
 

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1999 Suburban K1500 LT 5.7 completely stock - rebuilt engine
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Discussion Starter · #3 ·
I did take a quick glance of the new board when it arrived and yea..I was not impressed, but 2 boards with same issue seems coincidental... (But of course,I went through 3 sets of bad O2 sensors in my previous post.so I can believe it). I will break out the magnifying glass and soldering kit and take a look. Im well set up for it. I will take some pics also and post...thks
 

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1999 Suburban K1500 LT 5.7 completely stock - rebuilt engine
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Discussion Starter · #4 ·
Can you clarify proper operation for me? (Note, I do not have rear window washer - barn doors)
a) so, the push button on the tip of the left handle of the steering column..is that only for rear wipers only??
b) when you rotate the left hand knob to MIST, is the pump supposed to come on at all...or does MIST imply that there is a mist on the windows and that a single wipe is supposed to clear it?
c) what I noticed with the PUSH paddle is that I had to turn it really far and hold it and when I did that, I got voltage..it was only around 9 volts, but seems enough to activate the pump. I guess I was not turning it far enough...
I am currently assuming a) is yes, b) is no an c) is just a worn switch, but there is nothing fundamentally wrong afterall and I simply wasnt turning it far enough (aside from broken pump line, leaking fluid tank which arenow fixed)
 

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I also have barn doors on the burb, and an escalade rear wiper switch for a project on my sierra.... it's not on the multifunction switch but a switch on the right side of the dash with all the blank plates... where the fog light and air bag switches are in pickups.

A... push button on end is to activate cruise control... the slide switch is cc on and resume. Resume can be scary if you accidentally hit it in town when it was last set to a highway speed... lol.
B... as long as you rotate and hold the button towards mist the window wipers will operate until you let it go.
C... I agree, mine rotates 1/4" and operates wipers with the spray until its let go.

Yeah I would agree that the boards are fine... for sure since you replaced it. They all have that problem though, so soldering is not a bad idea.

Al
 

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Discussion Starter · #6 ·
Yup, thanks...i knew the end was cruise control also..not sure what the hell I was thinking....getting forgetful these days. I think this discussion can be closed out....thank you kindly for the help...
 

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No problem. Have a good one!
 
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