NSW Corvettes
Technical Tips => Electrical-Electronics-Air-Lighting-Guages-Security-Vacuum => Topic started by: Vettech on May 15, 2021, 11:34:15 AM
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Any one out there with GMFSM Electrical Supplement for 1990 Vett.
I have several (2) plugs floating under the centre console.
1. A black 2 pin plug c/w a black wire & black/white stripe wire.
2. A black 8 pin oblong plug c/w six wires only.
The 2nd plug has a mounting pin, I think its safe to assume this has a module with flying lead that plugs into it, thence its mounting pin is snapped into a retaining hole in the console hardware. The wires then run forward into/under the dash centre instruments, there are no unplugged modules ??. The only optionable module fitted in this area is the switch for FX3. But this option would at a guess require no more than four (4) wires which should run back into the ABS box behind the LH seat. There are no FX3 shocks, actuators, harnesses, controller's or console switches fitted to vehicle. These plugs are not present on my 87. Any ideas muchly appreciated.
I have a 1990 cct diagram which equates to my 87 book as 8A - 20 - 2 but its in conjunction with page 3, but I cant find anywhere a copy of the 1990 page 3/or second half of the working ccts for Automatic transmission - any help here would be great.
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Doug I would reckon the black pair is for seat belt warning light /alarm normally drivers side stalk has a switch incorporated into the head of stalk.
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Ummm thats not a bad suggestion Geoff.
I know I looked - there is two wires going down to my RH drivers seat, they disappear down behind the console side cover.
Maybe - its an option for the original passenger seat (RH side)
I think one is earth, but with ignition on, the blk/wht has power on it. Ummm something to follow up tomorrow depending on how deep the snow is. Its cold out there now.
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The belt stalks look like early Holden Comodore without any wires attatched to either.
So I tink your suggestion "its the seat belt alarm" is correct.
This car has no seat belt alarms I can see - plus I've now made the mistake of pursuing structual issues in the console and the centre console plate and its equip alignment etc. I should have left well enough alone.
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I can get the stalk with a switch in it seat belt light should stay on when car started for about 10 seconds. The switch in stalk is another parallel path until seat belt buckle is engaged then light goes out.
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Those two wires, I thought were for seat belt - pretty sure they go down around into the centre glove box, it has a mercury switch and lights when glove box lid is opened. I gave the light switch a clean and painted white the surfaces behind the globe (T5) and the green LED indicator for Fog Lamps on.
Both are now much brighter, great at night, but I can actually see the led now in the daylight. Found the main Instrument shroud had been previously repaired and re- cracked - so the glue is setting. Love Corvettes.
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I would have thought the glove box light would be orange & black
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Quick question - I'm not near my books - the seat belt switch is what ? NC or NO when the belt NOT inserted ?..
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One would think nc to make the circuit to illuminate the light.
Si
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This is a C4 complete with electronics Bfit, between the belt switch and light there is most likely a motza of electronical bibs and bobs.
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Someone said to me once that there only switches.
Bfit
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Yes well said Bfit, there is nothing like "Boolean Logic".
Which is like getting thru a Gate or two or is it like jumping thru hoops?
Needless to say I'm home now, and referring to the Gospel according to GM - it shows that the seat belt switch is an "NC" contactor.
Supplies earth to the Audio Alarm Module's A2 input (C4 84~89). A quick glance at the cct below shows that AAM then switches or flashes the "Fasten Seatbelt Lamp".
Once belt is buckled, the cct is opened and removes the earth from the "A2" input. Which now answers another question, the loose plug in the centre console, its open cct, ergo no seat belt alarms, since I need to get under LH footwell to restore relays & fittings etc back to normal, I'll remove the seat for ease and double check the seat belt fitting to ensure there is no switch.
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Any members out there with a GM 1990, 91 or 92 Electrical Diagnosis Service Manual Supplement, or if you have seen one for sale in Oz or could lend me. I have the 87 book, but as you all know the C4 Series 2 commenced in 90 and included a lot of changes esp in the electrical, electronics and dash/consol and wiring.
Please let me know, with warmer weather, I'm about to pull the RH seat out to find/fix these nagging irritating intermittent electrical faults. Untill found I suppose ill just have to be the passenger in the wifes Mustang. Of couse it also depends upon my latest bout of Gout in the right knee - which does tend to knobble ones movements, esp those requiring one to crawl head first upside down under the dash.
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OK a big thankyou once again to Uncle Burton (batee.com)
Always very helpfull.
He had some 90 circuit diagrams, see one attached.
My "security Indicator" is currently not working, and is one of several iritating minor electrical issues. I suppose we will start with the fuse and work our way to the globe. I'll get a pic of the "under dash" layout soon - this will give you an idea of the mess created by converters that us owners have to put up with.
Hopefully a wire, connector or splice, if its the bulb, then out comes the Instrument Cluster, and at this stage of disassembly it may just take four (4) more screws and it should unplug and pull out - of course once out, we may as well go over it and check everything.
Of course this is the simple side of the probable cause, the Central Control Module (CCM) switches this lamp on and off, and requires "X" number of inputs on its gates to give the desired response, so the search may become more involved.
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to check the fuse Doug just see what also is on same fuse. My first point to test after fuse would be to remove instrument cluster you then can test to prove + & - sides of circuit
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Yes I relented and removed the 4 x 7mm screws and pulled the instrument custer, but had to take front clear lens off before I could wiggle it out, since I could not find the bolts holding the steering up, which Youtubes say must be released to give the space.
Any way, there are twenty (20) mounted bulbs, cleaned and tested A-ok, also there is a bulb in the OD hole but it has blanking plastic piece blocking any light, the bulb is connected via copper traces on the PCB, so this answers my question from way back about the Over Drive light in the Series 2 C4's. G.M obviously thought it was too much of a distraction, so blanked it off.
I prefer the earlier flat digital IC, the colours are better and brighter, but as you can see this style is a complete unit, fully self contained and simply plugs into a captive socket in the rear of the cradle.
Alas i have not found the fault/s. Thanks Geoff, I now have several cct diags downloaded from Batee, but can't print as yet because "SHE" who currently works from home has used all the printer Ink, and we are in a bad Red Zone lockdown so are trapped.
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I don't believe I'm saying this, but 'B's company has directed her to "clear out her desk", but because we are in a "Red Zone" of contagion, she has had to apply to the NSW Gov't for a .......... wait for it........ a "Travel Permit" (home to city return) isnt that what we used to get along with "Smallpox" shots to go into less than savoury countries 50 years ago. We are both 2x AZ permit holders, whilst I believe in democracy and desease control - and yes they can easily co-exist, it appears that "Joh's Police State" is slowly moving south and taking hold.
Whilst the measures taken by the NSW Gov't are generally OK, there overall application and black & white dispensing leaves a lot to be desired. I appreciate that political statements are not wecome on the forum, but, enough is enough.
Recently a member on "H Plates" was told by RMS he could not re-register his car because they did not want him visiting their office, since people on "H Plates" must present a paper pink slip c/w other paperwork, "Their rule" as it cant be done electronically, he must wait till pandemic over. Now I dont know if that is a blanket across NSW rule, whether it was sorted by cooler heads or what, it would be good to see if any other members had the same issues.
I'll finish raving now since my blood pressure is thru the roof and to make matters worse its raining.
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Amazing the info out there, whilst my colour glossy 1990 sales brochure shows an OverDrive lamp on the Tacho half of the IP, I've found it is not there, the globe, wires pcb cct etc are, but the dial is not silk screened, and in a newly acquired GM technical training manual, covering the Central Control Module, a lamp layout diagram points to the spot and says "Vacant".
After reading, I now realise this CCM which they state is exclusive to the 1990 Corvette is the fore runner of the Body Control Module.
It does everything except the engine which is still done by the ECM.
This means things like VATS - passkey security, and doors, hatch, keys, AC, seatbelts, everything all feed one way or another via the CCM, and it it is all tracked, generates codes and can be diagnosed.
My new book covers how to get codes out, what they are and most important - how to reset them. This book is not the "be all end all" and is a handout to Qualified GM US Dealership Techs to upgrade them on the new features associated with the 1990 onwards.
So the Instrument panel is back together (with no left over parts), all checks out OK. NOW to get in and under the dash for the intermittent faults. I've some pics, which after they are schrinkted I'll post up. This was easy to pull apart, fairly straight forward, but i could not see any easy way to upgrade to LED without buying special led/globe fittings. The bulbs are a 161 and the globe is soldered and likely glued to the plastic base.
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I'll work on those pics, in the meantime, after being upside down head first under the RH dash, I can see where all the drivers AC air is going - straight out of the duct via 2" dia hole, not sure if this is a compromise from the LH~RH conversion, but the air basically floods the area under the dash, but with all pads and covers on, the air cant go anywhere but back into the return port, ergo bypassing the drivers vents completely. One glue job is being formulated.
Another thing I found was a relay hanging around doing ??, what is it for ??. With Pink, Orange, Black, Pink/ black stripe wires.
As dark set, I can't find its function, my limited 90 downloaded cct diags don't show it, neither do my 87 books, unplugging and trying everything from H'lights, Interior, fog, start, hatch, AC, parkers, etc etc..... maybe in the morrow and with a metre it could be the rear hatch de-fogger.
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Ok, after much ado, and confusion, we have three relays, two mounted on a plate, one has fat yellow wires and once pulled proved to be the "start" relay, whilst the one mounted next to it with 2 brown, Lt green, Grey wires proved via stephoscope to be the AC compressor relay. These wire colours are confirmed from the downloaded diagrams That still leaves the 3rd hanging relay, its black wire is earth whilst its Red is 12volts always.
No end of pressing buttons, or listening for a click can I determine what it does. I've a gut feeling its the fuel relay, and the car now cranks over several times before starting, and I'm probably going deaf, but I cant hear the fuel pump pressurise the fuel rail prior to cranking. With good Oil and Oil pump it is theoretically possible to start on the Oil Pressure Switch.... ummm .
This relay checks out OK. BUT I can't find a cct dia on the web.
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OK, found it, another obscure little diag on the net.
And the only buttons I did not press was the Radio, yes its the Amplifier relay, for the supa dupa Bose System, and the only section in my 87 book I did not look at was the Radio etc, and yes the wiring, type & colours are a match. Done!.
But before I put it back together c/w the Instruments, I'll just double check the pump operation & relay.
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I find the colour codes on wiring doesn't change from one year to another so the relay you can't identify you will probably be able to identify from 87 circuits, when i was reading your description of relay with yellow wiring i automatically thought of starter relay which you went on to identify. What colour are wires on relay you cant identify
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Thanks Sirfixalot. Got them all sussed out, the Start Enable Relay, the C68 AC Compressor Relay and the mysterious Bose Amp Relay. Also my fuel relay and pump are OK, age and the higher level of padding and insulation prevented me hearing it run.
I filled the 2" hole in the vent ducting, now I get a good level of AC coming out the RH face vent. However other holes and ducting mismatches, once corrected will also increase the air flow. Once again I wish I had bought one of those optic fibre camera's, you know the ones you stick in tight places to see thing's. Between limited light, access and head cramped up under the dash, I think when they mounted the Steering etc (chain&bar), they ground/sliced a section out of the AC Fan housing body to clear the mounting bolts.
Upon running the AC - I can feel air and hear the fan, but can't see into the tight space, I'd hazzard a guess that there is a ~ 20mm hole or oval hole thats leaking air and most likely screwing up the fan's ability to operate at max efficiency.
I'm becoming an expert at using Black Silastic sealant, it amazing where you can stick it, paint it, plaster it to overcome the shortcomings of previous converters. I still have one small corrugated duct that feeds the vent directly under the steering wheel right between the drivers legs, the ................... cooler vent.
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Sirfixalot - question.
I'll try to get a pic up, but do you know what a three (3) pin plug with Black and a White with black stripe wires would go to.
It too is hanging under the RH steering column, I've paired up all moduls and plugs, the only other two wire plug is the Orange&White which I'm sure is for the foot well lighting.
Also armed with Dentist pick & a sneaky mirror on a stick I've proved there is a hole in the air box, which now has a piece of Corflute type material cut and pasted into place, blocking and sealing the hole. Its amazing how much more air comes out where it should once these mongrel holes are sealed up - soon it will be toooo cold in the drivers seat - heaven forbid !....
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Looks like it clips onto something sheet metal will have a look tonight first thing that came to mind was vats with 2 wires but plug is totally different, maybee key chime alarm but that is normally incorporated into harmonica plug for blinker switch
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Another question.
Accelerator pedal has the spring loaded foot pad, but the whole pedal is pivoted further up where it bolts to the firewall.
Is there a spring meant to be in there ?, otherwise its just the weight of the lower half of the pedal that pulls the cable centre back.
Not sure I have this well thought out, but I know there is a heap of travel in the pedal before it even starts to pull the cable and start accelerating. And since we all know just how powerfull these little C4 babies really are, I feel I'm not getting maximin bang for my buck.
And yes you guessed it, the pedal is out of the car.
(Pedal also needs some metal removed as its interfering with other bits.)
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If the distance between the firewall and pedal isn't correct you will end up with slack before throttle starts to open you can slit a small piece of metal tube length wise and slip onto cable between ball end and pedal then close up with pliers, to make more responsive. I had a new cable made for RHD and had an adjuster put in cable between bracket and throttle body arm. If you change the pin on throttle body to a ball stud a holden HJ about 1300mm long will fit and is available on ebay.You also need to adjust TPS to get max voltage at wide open throttle,then adjust the auto kick down cable to suit, kick down will prevent WOT if not adjusted correctly. Cable pulls back from throttle body no spring on pedal
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Yep its not Vats, today I modified some towel rail approx 40mm long, some black Silastic, and my last piece of ducting is jointed up very nicely, whilst checking, the car would not start, bloody hell what now, and a plug kept poking into my eye...... Ah! Plugged it back together, and after a wait car started, well at least Vats and the key resister etc are working Ok. (Its a very small 2 wire plug/socket).
Not the one I'm chasing though.
Started to rain again, anyway the Silastic needs to set, save more for tomorrow, when I'll try the Instrument panel back into place, test for any issues, there are days stuck up under dashes that I wish I had the statue of a small brick laying person, they get it so easy!..
Regards.
P.S. have not re-installed the Pedal as one bolt is cross threaded, I wish Bunnings was open, although they dont sell individual dies or taps for that matter, maybe I'll sneak down to see the Wilton Oracle. Get my black balaclava on and run Blockades.
Oh and ........ "Goodbye Glady's".... I'll miss you at the morning Covid19 updates (LOL)
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Gladys for PM.
Bfit
Ps a year and a bit to next federal election, timeframe’s about right.
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A Glady's one day, a Barilaro the next - we go thru Pollies like a dose of salts.
Anyway. Put the Instrument Cluster (IC) back in place along with enough other bits to allow power up and test.
Alas Grasshopper, we still have issues, the IC is a "plug in" arrangement (see below) the plug is set thru the main PCB, those little silver spots are the ends of the pins and plug into the socket which is captive in the base of the IC cradle. But the socket is proud of the back plane and SHOULD plug right thru the PCB, one glance at the arrangement smacks of potential problems. Once in, all systems came on, but whilst securing, lights etc started to flicker on and off, any pressure on the IC diametrically above the plug gave varying results, also any pressure up under the rear of the cradle behind the wires going to the socket also gave varying results.
I can only hope that its not the wires, but the plug socket not mating correctly, it definitely does NOT have that solid plug into socket feel that I believe it should have.
Other than the swaping from LH to the RH side of the dash, the cradle has no modifications that I can see, but it may be warped enough to allow the pins at one end to be not correctly seated. But! After perusal of the connector cct/pin layout, I feel that unless we have one earth or power wire crook, then it is an overall plug/socket seating issue. AND.... requires the IC to be removed again, if only I had a new clean plug that I could set up up to test every cct. If only.
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Doug they are available on ebay seller is chrishartung seems to have lots of plugs,connectors,crimps, I was going to buy some off him when I had trouble with injector outputs on computer
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Thanks Sirfixalot, I'll look into that.
However after another close look, it looks like the metal bracket the cradle secures to is not GM, looks bent / warped, so I removed the two and 1/2 screws - yes a broken off 1/2 screw, this released the cradle from the metal support right at the connector (there is sufficient other support) and the IC now plugs in with a very positive feel, and like magic, it all comes alive & works well. I then went to town on the dash etc to try and bring the fault back in, thankfully everything is ok. Success at last.
Now to find those vanishing screws and put it all back together - but thats tomorrow.
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Well except for the lower footwell padding and lamp, its all a goer.
This 90 is what is known as a "so called" Chain&Bar conversion, as opposed to the "Mirror conversion" of which I'm well and truely fed up with, as far as handling, responsiveness and ease to work under the hood, these C&B's are as good or better than the Mirror's.
I would suggest to anyone with series 2 C4's (i.e 90 onwards) with Instrument Cluster issues to look to the connector at the rear of the cluster.
Now for those pesky seat pumps - but thats a new thread......