tom04Z06

I'm having problems with my power windows, the passenger window wont go up I test at the motor and it gets 24V when the down button is pressed but nothing when the up button is pressed.
Is the control supposed to reverse the 24V dc signal to and go up and down, and if so is it the control module bad or the switch on the door.
I confirmed that the down signal stays on when the button is pressed for a short time to facilitate auto down operation.
That control is $600.00 I want to be sure I need it.
Any help would be greatly appreciated.

HPS MASTER TECH

i don't think your supposed to see 24 volts there. change the module.

tom04Z06

OK thanks, I just bought a used one online for less than $100. I'll see what happens.

v8srfun

You should only see battery voltage if you have 24 there is a serious issue

tom04Z06

My bad I meant to say 12 volts at the motor.
I guess my real question is does the window motor switch polarity to change from going up to going down.
If this is the case I'm sure the control module is bad because I hear the relays energize for both operations but only voltage for the DOWN operation gets sent to the motor.

Greg_E

Yes. Both wires on the motor are grounded when the the switches are in the center (off position) When the door module receives an input it switches one of the grounds to 12 volts to turn the motor CW or CCW.

See attached file.

I assume you have checked the window operation with both the drivers and passenger door switch for the passenger window, and neither one worked.

tom04Z06

Thank you so much, your description of the operation and the diagram makes it much clearer. Yes the passenger window doesn't work with either the driver or passenger switch being pressed, and I hear the relay being energized for both operations from both switches. I think this confirms the diagnosis of a bad control module, given that I get a down signal to the motor but not the up signal. Would I be correct in assuming that if the ground is present and switched for the down operation then it should be available for the up operation if the module was operating properly?

Greg_E

I've never taken that relay apart but from what I've read it is two relays in a single package, so yes, one of the relays could have a bad contact for the 12VDC to drive the window up. The fact that you can hear the relays pulling in when you press the up/down switch rules out the switches or a bad connection on the input to the door module. The fact that the motor runs in one direction rules out a bad connection between the door module and motor.

While we are on the subject, I found the part number for the lock relays but not the window relay. Does anyone have that part number and source?

tom04Z06

Again, Thank you so much, I feel really certain I'm replacing the correct part.

Greg_E

Looking at the door module schematic and the spec. sheet (at the bottom of this post) for the two variations of that relay it looks like it could be the the 551-EP2-3N1ST separate type relay. The door module schematic shows the normally closed contact sitting at ground for both relays, so only one coil would need to be energized to provide the 12VDC to the motor. There isn't enough info on the schematic to say for sure.
It looks like the H bridge style is also used to drive DC motors in forward or reverse but looking at the spec sheet diagrams and comparing it to the door module schematic the separate type relay looks more like the one. Having said that I think the circuit board schematics are simplified to make them easier to understand.
Without having one of the modules in hand I can't say for sure which one is correct.

New information 7/26/17:

Thanks to forum member foamypirate for the pictures. At least for this part number the 551-EP2-3N1S is the correct relay for the window Up/ Down.
The last picture is an older version of the door control module. Note the different placement of the window relay. I can't find a picture of that board that doesn't have a label covering the part number, so I can't say with certainty what part number relay was used. If anyone has one they can look at please post a picture.

TorchCoupe97

I have just repaired my drivers window problem, I found the module connector J2 and J3 had corroded pins and a loose fit one too, which go directly to the motor. The J2 and J3 connector can be disconnected with a flat blade screw driver pressing in the connector side.

tom04Z06

Hi Greg,
I'm happy to report that the windows are working now the new control module, and again thank you for all of your help. I am new to this and any forum so I'm not used to having so much high quality information at hand I attached the pictures I think of my old module and the new one did look different although I don't have any pictures of it

, hopefully I have the upgraded version now

Greg_E

I can't quite make out the part number on the NEC relay in the upper left corner of your photo, but it looks like it might be EP2-3N1ST. Can you reply with the part number?
Does the relay look like it is the original part? If it was replaced at some point, the silicone coating at the base of the relay would be cut away in order to replace the relay.
In the time you've owned the car has that window ever worked? I'm trying to determine if that is the original relay or if someone tried to repair it at some point, possibly with the incorrect part. If not, then some boards were designed for the EP2-3N1S and others used the EP2-3N1ST.

It appears that there are at least 4 variations of these modules for both the RDCM and the LDCM. To my knowledge they are all interchangeable if they are the the same type (can't replace RDCM with LDCM etc.) but, if you want to repair them you need to look at what you have in order to get the correct replacement part. The lock relays can all be replaced with the Panasonic JSM1-12V-5 from Digikey but from what I'm seeing, the window relays may be different depending on the board.

If you have some soldering skills you can probably repair that module for around $15 including shipping cost.

When I came to this forum about the only thing I knew about the C5 Corvette was that I liked it. Many people have helped me over the years so I try to help where I can. There are many guys here that have spent considerable time helping others. I think I speak for all of them when I say, All we ask is that you post the resolution to the problem whether we were able to help you or not.

Glad to hear everything is working.