Author Topic: No intermittent wipers, no park  (Read 325 times)

Offline raysr11

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No intermittent wipers, no park
« on: November 09, 2018, 10:37:26 PM »
So, new motor, new pulse board and still no intermittent and no park, lo  and high run at the same speed.  '85 C10 Silverado tilt wheel.  The only thing left is the switch, right?  They're more money than the motor or the board.  Has anyone ran into this? 

Thanks
« Last Edit: November 09, 2018, 10:47:47 PM by raysr11 »

Offline hatzie

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Re: No intermittent wipers, no park
« Reply #1 on: November 10, 2018, 04:09:39 AM »
On the surface it would seem that would be the next step.  However... I've found the switch to be the most reliable part of the circuit. 
I've gotten new wiper motors and new delay modules that failed to work properly right out of the box. 
This sounds like a bad delay module...

The switch or motor could be bad but I'd troubleshoot a bit before you throw more parts at it.  Troubleshooting only costs a little time...  changing the wiper switch inside the column is a tedious job that you don't want to do if the switch is working.

What happens when you plug the switch directly into the cab harness without the delay module?
This completely bypasses the delay module to see if that's the problem.  HI, LO and OFF (Park) should work without the delay module in the circuit.  Obviously the resistor steps between OFF and LO will do nothing without the module in the circuit.
If that doesn't work test the motor...
Some theory of operation...

The switch controls the motor by grounding Park, LO, & HI and has a loop with steps of resistance to the outside legs on the delay module between OFF (Park) and LO positions. 
The Mist switch position grounds the HI wire til you release the switch and it springs back to OFF.The delay module should ground the LO connection on a delay timer corresponding to the resistance it sees from the switch loop and pass HI, LO, and Park grounds straight through. 
The wiper motor has two plugs.  Park and Run.  The Park connector has two wires (LO & PARK).  The Run connector has three( HI, LO, IGN).  These are both unsealed Pak Con II plugs with terminals that are easily accessible to a probe from the rear without unplugging them. 
The wiper motor is provided constant ignition power on the white wire in the Run plug.  If the motor turns at all the white wire is hot with the key switched on. 

It's easy enough to test the motor operation with the ignition switched on using a test probe attached to ground on one end.

Do the wipers park when you ground the Black wire with a Light Blue Stripe? 
This wire should be grounded when the switch is set to OFF.  The Park switch inside the motor closes the connection between the Black/Lt-Blue Park (OFF) wire and the Gray LO wire. A cam opens the Park switch inside the motor when the wipers reach the bottom of their sweep.  When you ground this connection the motor should run til the arms are parked.  If it doesn't park by directly grounding the Park terminal the parking switch or the LO winding inside the motor are screwed up... or the splice in the Gray LO wire is borked.

The GRAY LO wire is connected to both the PARK and the RUN plugs.  Does the motor run when you ground either Gray wire?  Try both Gray connections.  While a harness issue isn't common anything is possible...  If the harness splice between the Gray wire in the Park plug and the Gray wire in the Run plug is dodgy the Park function will not work.
Does the motor run when you ground the Purple wire terminal on the motor?  This is the HI connection.
« Last Edit: November 10, 2018, 09:46:35 AM by hatzie »
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Offline raysr11

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Re: No intermittent wipers, no park
« Reply #2 on: November 10, 2018, 07:50:34 PM »
Thanks for the reply.  The first thing I did was to get another delay module, used.  When that didn't work I tried a new motor.  Same thing.  So I thought that maybe the used delay module was bad too so I tried a new AC Module, nothing changed.  So I hooked the plugs together, no change.  There is only one wiper speed, no change from high to lo.
I will check it tomorrow using your method.  Thanks again.

Offline raysr11

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Re: No intermittent wipers, no park
« Reply #3 on: November 13, 2018, 10:39:47 AM »
Here's what I did following your instructions:  The motor runs when the upper gray wire is grounded and does not run when the lower gray wire is grounded.  No park when the black/blue stripe wire is grounded and it doesn't run when the purple wire is grounded.  So, the motor runs at the same speed, I'm thinking low, doesn't park and has no delay.  I had the plugs under the dash hooked together w/o the module for these tests.  Thanks again.

Offline hatzie

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Re: No intermittent wipers, no park
« Reply #4 on: November 13, 2018, 09:39:39 PM »
OK
You have a motor and probably a wiring issue.
It runs on LO so your motor power wire has juice the way it's supposed to from the ignition and the gray motor LO wire on the three wire RUN plug is properly connected back to the switch.

Unplug the delay module from the cab harness to isolate the switch wiring out to the motor.
Unplug the Park and Run plugs and buzz from gray to gray with your meter set on resistance or to the continuity buzzer.  Both wires should be spliced together in the harness so the ohmage should be Zero or darn close.  The gray wires not being spliced together would be at least part of why it doesn't park and definitely why it doesn't turn on when you ground the gray wire on the two wire park plug.

If the motor doesn't run when you ground the Purple HI connection on the RUN plug, with the ignition switched on, the motor is knackered plain and simple.
Your delay module could still be smoked but let's get everything else working before worrying about that.
« Last Edit: November 13, 2018, 09:56:25 PM by hatzie »
SVC & wiring mans --> Here http://tinyurl.com/7387BRD-SVCMAN or My Bucket @ http://tinyurl.com/SQ-SVCMAN
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Offline raysr11

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Re: No intermittent wipers, no park
« Reply #5 on: November 14, 2018, 11:08:05 AM »
"Unplug the Park and Run plugs and buzz from gray to gray with your meter set on resistance or to the continuity buzzer.  Both wires should be spliced together in the harness so the ohmage should be Zero or darn close.  The gray wires not being spliced together would be at least part of why it doesn't park and definitely why it doesn't turn on when you ground the gray wire on the two wire park plug."

'Park and Run' is the top 2 pin plug?  'Buzz'?  What's that?  The 'gray' wires, the top gray and bottom gray ?  I'm not familiar with the terminology.  Thanks for your patience and help.

Offline raysr11

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Re: No intermittent wipers, no park
« Reply #6 on: November 14, 2018, 08:40:57 PM »
The two gray wires have no resistance.  The gray wire on the two prong  plug when grounded will run the motor provided the two plugs under the dash are connected to each other.  The motor won't run from the purple wire when grounded.

Offline hatzie

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Re: No intermittent wipers, no park
« Reply #7 on: November 15, 2018, 09:57:59 AM »
OK then the wiring is probably just fine.  It is odd that the gray wires don't have continuity til you plug in the switch...  I believe the splice is on the engine side of the wiper sub-harness.

Park is the 2 position plug.  (OFF[PARK] & LO)
RUN is the 3 position plug. (IGN, LO, HI)

The purple wire on the RUN plug is HI.  If grounding that terminal doesn't turn the motor on then the motors' HI winding is dead or knackered or ...  An autopsy might reveal what failed but I doubt it's easily repairable.

Buzz is a term used to describe testing using a meter set to the continuity position.  The buzzer, or whatever you want to call the piezio speaker, makes noise in the meter when there's current flowing from one probe to the other in the continuity test position.  Not all meters have the continuity test position but the common meaning of "Buzzing a connection" is a resistance measurement where you're just looking to see if the wires are open or making contact.  Buzz is much shorter than writing a book to describe said action.
« Last Edit: November 15, 2018, 10:04:32 AM by hatzie »
SVC & wiring mans --> Here http://tinyurl.com/7387BRD-SVCMAN or My Bucket @ http://tinyurl.com/SQ-SVCMAN
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Offline raysr11

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Re: No intermittent wipers, no park
« Reply #8 on: November 16, 2018, 10:32:18 AM »
Thank you for your help.  The new motor I tried didn't have enough power to drag the wipers across the windshield dry, whereas the stock one, 33 years old,did.  I suppose that the new motor, also could have been bad too.  It would seem that out of 3 delay modules one would be good, one new and A/C.  So, I'll try another motor.

Offline hatzie

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Re: No intermittent wipers, no park
« Reply #9 on: November 17, 2018, 02:30:56 PM »
The 78-83 and 85-91 wiper delay modules can usually be repaired by a competent electronics tech. 
Unlike most automotive control systems now.  It's a fairly heavy through hole PC board with...  One or Two or Three FETs...  At least one Microchip... and several diodes, resistors, and capacitors. 
Usually 25+ year old Electrolytic caps are in less than reliable operational condition.

I've repaired several of the older pulse modules with a handful of new electrolytic capacitors.  Never opened one of the 85-91 units up but I expect they would respond to the same treatment. 
Just like removing and re-installing ignition modules... replace the heatsink paste on the FETs.  I shy away from the sliver bearing heatsink compounds because they're conductive.  It's safer to stick with the good old fashioned white heatsink paste.
« Last Edit: November 17, 2018, 02:37:15 PM by hatzie »
SVC & wiring mans --> Here http://tinyurl.com/7387BRD-SVCMAN or My Bucket @ http://tinyurl.com/SQ-SVCMAN
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Offline raysr11

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Re: No intermittent wipers, no park
« Reply #10 on: November 18, 2018, 05:10:54 PM »
How can I isolate the switch and test the motor?  I tried unplugging it underneath the dash to try and jump power through to the motor but failed at that not knowing what wire to use.  I haven't purchased another motor as of yet so I'm still trying to determine which part is bad. 

Offline raysr11

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Re: No intermittent wipers, no park
« Reply #11 on: November 18, 2018, 06:01:25 PM »
Inside the cab with the delay module disconnected on both ends the black plug is hot on the purple and gray wires only.  The color of the wires in that plug are pink, purple, black, gray and black with blue stripe.  Under the hood all the wires are hot with the switch off except the black with blue stripe.

Offline raysr11

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Re: No intermittent wipers, no park
« Reply #12 on: November 18, 2018, 06:06:41 PM »
And, the motor doesn't run when probing any of the wires under the hood from the rear of the plugs with a test light.

Offline hatzie

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Re: No intermittent wipers, no park
« Reply #13 on: November 19, 2018, 12:00:36 PM »
Download the 1985 GM wiring diagrams. http://www.73-87chevytrucks.com/techinfo/7387CKMans//Wiring/ST_352_85_1985_Chevrolet_GMC_Light_Truc_Wiring_Manual_CK_10_30_Only.pdf

How can I isolate the switch and test the motor?  I tried unplugging it underneath the dash to try and jump power through to the motor but failed at that not knowing what wire to use.  I haven't purchased another motor as of yet so I'm still trying to determine which part is bad. 

If you're trying to put power on these wires then you didn't read paragraph 4 of my first post in this thread...  The switch is on the GROUND side of the circuit.  It switches Grounds to the motor. THERE ARE NO HOT WIRES IN THE SWITCH WIRING.

GM Circuit #s
  • 150 BLK is the main ground wire for the switch.
  • 91 GRY LO GROUND FROM SWITCH LO and DELAY MODULE This splits at the firewall and runs to both the PARK and RUN plugs.
  • 92 PPL is HI GROUND FROM SWITCH HI
  • 93 WHT is IGNITION POWER to motor (and washer motor) This wire does not originate from the switch. IT'S DIRECTLY FROM FUSE PANEL.
  • 94 PNK is WASHER GROUND FROM SWITCH
  • 96 BRN is the stepped resistance for the delay module  THIS WIRE PAIR IS ONLY ON THE SWITCH... plug positions A & G.
  • 97 BLK/LT-BLU is PARK GROUND FROM SWITCH OFF



The only HOT to the motor is supposed to be from the Ignition switch through the fuse panel on the Circuit 93 WHITE wire. 

Inside the cab with the delay module disconnected on both ends the black plug is hot on the purple and gray wires only.  The color of the wires in that plug are pink, purple, black, gray and black with blue stripe.  Under the hood all the wires are hot with the switch off except the black with blue stripe.

Black is the main Ground for the switch.
Pink is the washer pump motor ground from the column switch. 
The other three wires go directly to the motor.  These are GROUNDS from the switch or the delay module.
If the PPL and GRY wires are showing voltage it's because it's backfeeding through the motor windings.


And, the motor doesn't run when probing any of the wires under the hood from the rear of the plugs with a test light.

I assume one end of your test light is on a HOT connection...  That will not work.  Hook it to a ground and probe the back of the Black/Blue, GRAY, and PURPLE motor wires connections with the ignition switched on.

Since the wipers move in LO I am making the assumption the wiper main power wire is providing 12-14.5v to the wiper motor with the ignition switched on.

If you ground the Purple wire with the ignition switched on and the wipers do not move the motor is knackered.
If you ground Gray wire on the RUN plug and the wipers don't move your motor is knackered.

If the motor ran when you grounded the gray wire on the RUN plug and it doesn't run when you ground the gray wire on the PARK plug the wiring may be suspect.  The gray wire is spliced at the bulkhead plug in the engine bay.
If you ground the Black/Blue wire and the wipers do not park then the parking cam or park switch inside the motor is suspect...  the motor is knackered.
« Last Edit: November 19, 2018, 12:24:39 PM by hatzie »
SVC & wiring mans --> Here http://tinyurl.com/7387BRD-SVCMAN or My Bucket @ http://tinyurl.com/SQ-SVCMAN
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Offline raysr11

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Re: No intermittent wipers, no park
« Reply #14 on: November 19, 2018, 04:26:12 PM »
Put on a new motor now I have lo, hi(doesn't see that must faster than lo) and park but no intermittent with the 2 used delays.  Seems like it's fixed once I get a new delay.  Thanks for the help.