Author Topic: Delay module for wiper  (Read 992 times)

Offline Wickman

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Re: Delay module for wiper
« Reply #15 on: February 04, 2019, 09:26:38 AM »
Shall I understand it as the compound shall be there in order to transfer heat? My transistor don't have that, see pic, so shall I now suspect the transistor to be "burned"? Can such a one be checked? I cant see any spec on it (perhaps on the back side?). The transistor is laying on a piece of white plastic/nylon.

Offline bd

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Re: Delay module for wiper
« Reply #16 on: February 04, 2019, 02:16:41 PM »
Replace the caps and smear a thick coat of heatsink compound on the exposed upper surface of the power transistor then reinstall the PC board into its case and test the module operation.  The thick nylon sheet below the power transistor is a shim to help press the transistor against the aluminum heatsink.
Rich
It's difficult to know just how much you don't know, until you know it....
In other words... if people learn by making mistakes, by now I should know just about everything!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Wickman

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Re: Delay module for wiper
« Reply #17 on: February 04, 2019, 02:56:20 PM »
I see. A big thank you for excellent assistance. You must be a professional automobile expert, not just an interested hobby enthusiast. I have read several of your posts here on the forum, and it is a true pleasure and very educating.

Offline bd

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Re: Delay module for wiper
« Reply #18 on: February 04, 2019, 03:31:39 PM »
Thanks.  I appreciate that.
Rich
It's difficult to know just how much you don't know, until you know it....
In other words... if people learn by making mistakes, by now I should know just about everything!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Wickman

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Re: Delay module for wiper
« Reply #19 on: March 05, 2019, 02:06:44 PM »
So now with all capacitors new on the board... No, still the same Four out of five operations work (Mist - holding knob to the left - Works, OFF Works -wipers park in right position- LO works, HI works). Pulse/delay DONT:
But there is something that I don't understand. The circuit with the resistor, how can it be any current running through that circuit? There is no positive lead to the delay module (except the one for light bulb). The entire wiper control is just handling ground connections, positive voltage goes directly from fuse box to wiper motor and washer rely.
And another clue that indicates that I am missing something is the sentence I read under the header "DELAY WIPER SYSTEM OPERATION AND DIAGNOSIS" in the Shop manual for 10-30  lighy duty trucks.  There is a sentence (with no explanation) that says: "There is also a lead from the control that plugs into the accessory cavity of the fuse panel". No more about that wire, just that. And on the electric wire diagram no such lead is showed, and there is definitely no such wire on my module.
Question remain: Where is the voltage level that push current through the variable resistor circuit?

Very curious if someone can answer this.

Andreas Wickman

Online MIKE S

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Re: Delay module for wiper
« Reply #20 on: March 05, 2019, 04:28:10 PM »
Did you actually measure the  variable resistor to see if it actually varies when turning the knob?

Offline Wickman

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Re: Delay module for wiper
« Reply #21 on: March 05, 2019, 11:14:40 PM »
No I haven't, but that was exactly what I was thinking could be next step. But even if that test shows that the resistance do varies while turning the knob, I think my question remains; how can the delay module work without any positive connection? Also loading the capacitors - how?

Offline bd

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Re: Delay module for wiper
« Reply #22 on: March 07, 2019, 09:40:58 AM »
I believe the module in your truck is a newer generation than that described in your manual.  Older pulse modules used a miniature electromechanical relay that is absent from the PCB of your module.  The dedicated power lead was used on the older modules with relays.  I think on the newer modules power is acquired through the high-speed circuit from the motor(?).  I will need to study the wiring diagrams further to verify this idea when time is available.
Rich
It's difficult to know just how much you don't know, until you know it....
In other words... if people learn by making mistakes, by now I should know just about everything!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Wickman

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Re: Delay module for wiper
« Reply #23 on: March 07, 2019, 12:34:09 PM »
Ok, an older version can be an explanation. Regarding supply of positive voltage to charge capacitors and to create a current flow in the varistor circuit I am now quite convinced it's coming to the module via the wash-trigger-coil. I have made a test rig and a clear wiring diagram. I will not leave this before I got it to work!

Online MIKE S

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Re: Delay module for wiper
« Reply #24 on: March 07, 2019, 01:49:35 PM »
interesting that you bring that up. On my 87 that has the turn stalk wipers and module at bottom of column, If I have the connector to the washer pump which is mounted on the back of the reservoir disconnected my delay wont work. 

Offline Wickman

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Re: Delay module for wiper
« Reply #25 on: March 07, 2019, 03:04:46 PM »
Well that's a proof that there is where the positive voltage come from.

Offline Wickman

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Re: Delay module for wiper
« Reply #26 on: March 08, 2019, 04:32:55 AM »
 :) GOOD NEWS, my delay module are fit for fight again. It was the tyristor that was broken. Perhaps overheated because it was lack of heat-transmission over to the aluminium fine-block when there was no heat sink compound upon the old tyristor.

Offline bd

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Re: Delay module for wiper
« Reply #27 on: March 08, 2019, 08:28:45 AM »
That's great news.  Very well done!  Do you have the part number of the component that failed?
Rich
It's difficult to know just how much you don't know, until you know it....
In other words... if people learn by making mistakes, by now I should know just about everything!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Wickman

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Re: Delay module for wiper
« Reply #28 on: March 08, 2019, 08:56:01 AM »
It was my "Computer-buddy" who had it in his "good-to-have-box". It was a true standard component he said, so I have e-mailed him now for the part number. I will forward it as soon as I got it. Further he said that also the IC was a true standard component easy to find (and so of course all the resistors also). This means that as long as you have circuit board intact, you are able to fix it. GOOD!

Online MIKE S

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Re: Delay module for wiper
« Reply #29 on: March 08, 2019, 09:57:47 AM »
I'm glad you got it working. This experience has probably given you a good insight on how the whole system works by researching and dissecting components. These days it's just remove old part and replace with another with no real clue on how things operate or why things fail. I come from old school were we repaired components instead of replacing them. On my own 87 the wipers were real slow so I was bound and determined to repair it. I peeled open the end of the motor and removed the armature. Cleaned up all the old and stiff grease out. Relube it and reassembled. Works as good as new. Now I have a better understanding on how it all works.