NSW Corvettes

Technical Tips => Post 84 => Topic started by: Vettech on October 03, 2019, 04:14:27 PM

Title: C4 1990 Power Windows
Post by: Vettech on October 03, 2019, 04:14:27 PM
New topic.

Any one out there with a schematic of 1990 power windows.!?

I have an Electrical Supplement for 87 but the 90 has its switches on the doors.

My RH (drivers) side just gave up the ghost.

Lately on google search I'm getting a trillion items from Europe, which upon opening trys to sign you up for an account. The sites are all different but the signup screens are identical.???
PITA!....      /size]
Title: Re: C4 1990 Power Windows
Post by: Vettech on October 03, 2019, 07:31:00 PM
LH works OK on either switch. So fuse Ok.

Took the door arm apart, listening very closely I can just hear noise like a motor straining to turn in either direction.

Swiches are not interchangeable.

Its at this point, with a big job ahead, you start to look at other things, decided to remove fire exstiguisher from glove box and put else where.

With G'box out I can see this converter has at least tried to do a reasonable job, but a 4" □ duct butting up to a 2" ○duct, with a 2" gap, no seal foam on any joins, an open 1"x2" hole on the air feed for the thermostat sensor - its no wonder, hardley any air comes out of the correct  registers.

Tomorrow we get foam seals etc etc...
Title: Re: C4 1990 Power Windows
Post by: Vettech on October 04, 2019, 08:20:29 PM
Well I decided that whilst parts of the dash & glove box are out  I'll try fix the ducting.

A bit of self adhesive foam /  rubber  etc and the pass side duct is pushing much more air.

Now some coreflute - you know the stuff they use for Realitor forsale or Politician signs.

Well after some fixup -  the pass side is much better, but now too dark, besides the boss is home.

Whilst closing up, replugged the window switch, put up LH side and you guessed it - the RH side is now working grrrrrrr....

I hate intermittent faults....... 
Title: Re: C4 1990 Power Windows
Post by: Vettech on October 20, 2019, 11:11:25 AM
Removed the DIC (Driver Information Centre) to check the LDR (Light Dependant Resistor). Keep in mind that the switch panel and the Display panel have been seperated at the time of conversion - unfortunately GM used a flexible plastic sheet as the cct board - reconnecting this for the new layout is a problem.

The LDR is a cadnium sulphide based resistor which changes resistance in response to light (photons).  (Two types avail Jaycar - use the lower restistance one)

So - bright sunny day, light floods into the LDR portal, resistance drops very low (2^ ~ 2K^) this drives the circuitry and the dash lights become bright.
As it gets darker outside, the resistance rises exponentualy, drives the dash lights down, ie dims them down.

The LDR can be replaced, they are not polarised, desolder and drop a new one in. OR - Short the legs with solder, gives very low resistance, dash lights on their brightest setting permanently. Did toy with this idea, but I like things to work as designed, so I planned to get a new LDR.

BUT - Whilst looking, with my ever decaying eyesight, I noticed an issue, upon re-looking thru an illuminated scope, I could see that one wire leg of the LDR was moving in the solder joint on the cct board, this would be a very HIGH RESISTANCE and would keep the dash dimmed down to off. And since it moved, would explain the changes from time to time that initially made me think it was partially working but the components had aged, and needed replacing.

Re-soldered, re-installed, seems to work, but now its night, I'll retest tomorrow, in the meantime I'll check the headlighrs grrrrrrrrrrrrr.
The headlights come on but once again the LH will not drive up.
Since I had to move the DIC wiring, I can only assume I have some intermittent wiring/connector fault under the dash.

Now back to searching for a cct diagramm, but puzzled by only one driving up - but both sides illuminated. I hate intermittents.

Hope this helps someone.

Title: Re: C4 1990 Power Windows
Post by: Vettech on October 21, 2019, 12:47:21 PM
Well found the problem with the LH Headlight.

The problem was intermittent, but when the hood is up - it all works fine.

On the 90 the plugs in the LH front valance are secured by a plastic spider, this prevents movement of the plugs when lights or hood are moving.

On 88 up the motors are two wire (grey & green on 90) and electronic module controlled, with a Grey plug and socket.

Close inspection shows it not pluged all the way home. Removed cleaned, wet rubber seal and pushed (hard) till it seated.

Only wet with water, since it dries and leaves no harmful residue, but allowes those green rubber weather seals to slide together easily.