88 all Electrical issues...

[the hellrazor]

Most of my Accesssorys just quit working yesterday 1988 C4; Climate Control, Stereo, Interior Lights, Seat Operation. Basically everything you don't need to operate the Vehicle. I suspect these things are all grounded to same Location? Something went ZAP behind the Dash and filled the Car with smoke once before a while back. I suspected the Rear Defrost Operation, so I pulled the Fuse as that hasent worked since I bought this Nightmare.. After that everything still worked fine.

But, yesterday I got in and fired it up and tried start the Defroster and it was DOA. Then I noticed pretty much none of the Accessorys worked. I order a Hanes Repair Manuel so I could have Wiring Diagrams(wont be here for 7days). If anyone has any ideas or knows were these things are Grounded please LmK... There is 1 yellow wire in the back of the Stereo with 12volts and 1 pink/black trace with 12volts in the back of the Climate control. But yea, I plug these things in and there completely dead.

[XQIZT]

Whoa...double check all the the fuses in the box in front of the passenger door. Possible fusible link when pop or a ground came loose.

We'll help ya find it.

[87vette81big]

Open the Hood on your 88 Vette.
Right Below the battery tray is a Fusible Link Junction post.
See if any of them are burnt or smoked.
Orange Fusible links on my 87 there. 88 should be the same.
Use a 12 Volt test light or Digital DVM to make sure each 1 is good if unsure.
Best to start here before climbing under the dashboard.

[wildcatlock]

Originally Posted by the hellrazor

Most of my Accesssorys just quit working yesterday 1988 C4; Climate Control, Stereo, Interior Lights, Seat Operation. Basically everything you don't need to operate the Vehicle. I suspect these things are all grounded to same Location? Something went ZAP behind the Dash and filled the Car with smoke once before a while back. I suspected the Rear Defrost Operation, so I pulled the Fuse as that hasent worked since I bought this Nightmare.. After that everything still worked fine.

But, yesterday I got in and fired it up and tried start the Defroster and it was DOA. Then I noticed pretty much none of the Accessorys worked. I order a Hanes Repair Manuel so I could have Wiring Diagrams(wont be here for 7days). If anyone has any ideas or knows were these things are Grounded please LmK... There is 1 yellow wire in the back of the Stereo with 12volts and 1 pink/black trace with 12volts in the back of the Climate control. But yea, I plug these things in and there completely dead.

Ground are on the drivers rear of engine, under battery tray on frame, passenger side on frame in front of fire wall there is one, drivers and passenger kick panel there is one in each IIRC, and a few in the rear on the frame rails. Hanes manual probably wont help much, find yourself a factory service manual. Much better and specific to your year, not 5-10 year span like hanes or chiltons. I agree with xqizt and 87vette about checking the fusable links and you can clean the grounds in that location while you are there. Battery tray removal also makes the grounds on the block much easier to access. As said above we will get you going, just follow the instructions youare given and dont take shortcuts. If the guys here ask for info in a certain way by doing a certain test, rest assured there is a reason for it. Very smart and knowlageable guys here.

[87vette81big]

Despite the age, our C4 Corvettes are very well built.

Thinking of the Electrical smoke smell you experienced prior.

Another area to check out is the Ignition electrical switch mounted on the lower steering column.
Have to lower the steering column & rest on the driver's seat to access. Leave the steering column attached to your Vette.
Only remove the the 2 13mm or 15mm nuts holding column tight under the dashboard frame.

12 volt test light is a handy tool troubleshooting electrical problems. DVM confirms problems & perform resistance checks on open circuit & voltage drop tests on live loaded electrical circuits.

Guessing & parts changing gets expensive & frustrating for You & us here trying to help out.

Troubleshoot 1st. Do Not Guess & change parts only.

[the hellrazor]

Having a hard time logging in. For some reason I type in my User Name/Password it says thanks for logging in, then just doesn't log in.

I have checked all the fuses. All in the box on Passenger Side are good, the 1 underhood by the Blower Motor and Core is good and Fuseable Links "look" good. Only way to really know on them would be to splice each one to test for Resistence across them right?
I'm already tore 9layers deep in to the Dash. And, behind the Head Unit for the Switches ubove Stereo there are 2 Relays I don't know what they are for yeat? I'm kind of worried the Harness may have gotten Fried??? I have not yeat seen any Burn Marks.
I really need to put it on Jackstands and get under it, being that there is still 2feet of Snow that PITA.
I just bought it as my new DD and I have already Burned 2 temp tags. It had two shorts on the fuel pump assembly and other minor problems found and fixed. Thing ran Great for about 2 weeks then this... Can't pass Inspections with these problems. I'll keep you guys posted on this and of course everyones advice is very appreciated!!

[Jake_Dragon]

I shorted my alt wire and it burned the links by the starter.
I replaced them but still don't have any interior lights
But everything else works.

Good luck

[wildcatlock]

Originally Posted by the hellrazor

Having a hard time logging in. For some reason I type in my User Name/Password it says thanks for logging in, then just doesn't log in.

I have checked all the fuses. All in the box on Passenger Side are good, the 1 underhood by the Blower Motor and Core is good and Fuseable Links "look" good. Only way to really know on them would be to splice each one to test for Resistence across them right?
I'm already tore 9layers deep in to the Dash. And, behind the Head Unit for the Switches ubove Stereo there are 2 Relays I don't know what they are for yeat? I'm kind of worried the Harness may have gotten Fried??? I have not yeat seen any Burn Marks.
I really need to put it on Jackstands and get under it, being that there is still 2feet of Snow that PITA.
I just bought it as my new DD and I have already Burned 2 temp tags. It had two shorts on the fuel pump assembly and other minor problems found and fixed. Thing ran Great for about 2 weeks then this... Can't pass Inspections with these problems. I'll keep you guys posted on this and of course everyones advice is very appreciated!!

Fuseable links can be tested with a simple testlight or dvm. Just check for voltage ( 12v ) at the ring terminal and also about 10-12 inches back up the wire past the splice point. Most times you can tell very easy if it is burned. Visually it will look the same, but if you wiggle or pull on the wire it will feel very stiff and have an obvious "broken " spot somewhere along the fuseable section. The relays you have in the center dash are horn and theft deturrent starter relay. There should also be a small fuse block in the same area. If nothing works my bet is on a fuseable link.

[87vette81big]

Wildcatlock is correct.

I like doing a TUG Test on each fusible Link I see & can reach.
Just pull on it with 5 to 10 lbs of force. If it pull free from either end, you found a problem.
Best to replace with special fusible link wire. Available from Napa, Carquest, Autozone, ect.

Something shorted out to ground or the body, chassis likely somewhere. Keep looking.

2 feet of snow ? Where do live ? In the Midwest ?
I am about 100 miles South Of Chicago. Interstate 80 near me.

BR

[mbwalker]

Do you have a volt meter?

[the hellrazor]

Originally Posted by mbwalker

Do you have a volt meter?

Been going crazy with my Multimeter since the first day I bought this Car. Found and fixed 3 shorts already. This one however is New. So I did look at the Fuseable Links kinda tugged on them. The next day said F'it. I needed the car earlier today started putting the Digi-Dash back in so I could use the Car. Well now everything seems to be working except the Digi-Dash lol... I plan on fully re-installing the Dashboard today, looking closer at all of them Links and Getting under the car and looking at the Ground on the Transmission/Block. This Salt Lake City Utah Weather has been shitty this year. But yes, I am thinking there is a Short on one of them Links and when I jiggled it re-connected? It's easy to find 1 end of each Link. However it's going to be hard to test each Wire w/out Splicing(other end vanishes in to the Loom usually). So yea, it is looking like a Short on the Power side... Will keep you guys updated.

[mbwalker]

Originally Posted by the hellrazor

I am thinking there is a Short on one of them Links and when I jiggled it re-connected? It's easy to find 1 end of each

Not criticizing, but that would be an "open" rather than a "short", if I'm reading it right. Just trying to help avoid confusion.

Opens are not too bad to find...just keep checking the voltage until you lose it.

Don't currently own a C4, but I am an electrical engineer.

Keep us posted!

[the hellrazor]

Update: I got it passed inspections. Accessorys are still working fine.

I still cannot get the Digital Cluster working(it worked fine before)!! It lights up and has power to it. However NONE of the Gauges work. And the Service Engine Soon light keeps come on, with Code 24- Speed Sensor (VSS) Circuit.
I opened up the Cluster and it's pretty obvious someone has been in there doing some work. Looks like a bunch of Solder Joints and 2 Resistors had Failed...

But yea, if anyone has any ideas i'm all ears. Cluster lights up but, none of the Gauges are working...

[87vette81big]

Originally Posted by the hellrazor

Update: I got it passed inspections. Accessorys are still working fine.

I still cannot get the Digital Cluster working(it worked fine before)!! It lights up and has power to it. However NONE of the Gauges work. And the Service Engine Soon light keeps come on, with Code 24- Speed Sensor (VSS) Circuit.
I opened up the Cluster and it's pretty obvious someone has been in there doing some work. Looks like a bunch of Solder Joints and 2 Resistors had Failed...

But yea, if anyone has any ideas i'm all ears. Cluster lights up but, none of the Gauges are working...

Its very likely the Power supply in your 1988 C4 instrument cluster.
If I remember correct, its mounted on a separate circuit board inside of the cluster.
Its a Modular or stacked circuit boards inside below the LCD Displays.

Its a switching power supply unit.
Someone was in there replacing the resistors because the original Ceramic bodied 10 watt resistors failed.

I have a spare 1987 A4 C4 instrument cluster in my basement.
Ebay find for $100. I used the Tachometer LCD display out of it to repair the non working Tachometer in my 87.

There are some links on the net that may help.
Others here should know where they are.

BR

[the hellrazor]

Originally Posted by 87vette81big

Its very likely the Power supply in your 1988 C4 instrument cluster.
If I remember correct, its mounted on a separate circuit board inside of the cluster.
Its a Modular or stacked circuit boards inside below the LCD Displays.
BR

Yes your correct about the power supply. I have been all through there with my Multimeter set to ohms. There is nothing burned and the entire power circuit in there show's continuity. Here is what is strange though. On the fuse box "3A Fuse INST"-I believe that stands for "Instrument" is completely dead 0Volts no matter were you move the Key. It had voltage the other day. I believe the Cluster was plugged in at the time. I currently have the Cluster tore apart in my Kitchen. Idk if It needs to be plugged in to have power there? I will put it back together and plug it in. If still no Power at the "3A INST Fuse", then i'm sure I found my issue. I'll update later and thanks for the help guys.