I'm still mostly a newbie and electrical is not my favorite thing to work on. But, I know I had to address this one..........I looked at my Chilton, searched the forums and online, read a couple other fusible link posts from the last few days, but still need some advice.
This first pic is of the front of my starter/solenoid. It looks like the P.O. did some work on this, as the "split wires" are green and blue, not red. Both have fusable links shown in the second photo. The S terminal wire (I believe it is supposed to be purple, but it's pretty discolored) runs up to the firewall behind the distributor to a connector setup.
The wire that is green off the solenoid goes to a fusible link (14 gauge) and then to a yellow, larger gauge wire. Then it was cobble-connected to the red wire that goes to the alternator shown in last photo. However, the blue wire goes to a 20 gauge fusible link, then a yellow wire and then it was completely clipped off and not connected to anything. It was just wrapped in electrical tape to the other green wire. So, I'm trying to figure out what to do with the blue wire issue. My Vette has the OE security system and I found it was completely disconnected. Is that where the "blue" wire was supposed to go?? I can't find a disconnected wire in the harness.
Also, how can I properly repair this to make the circuits safe?? Should I just get a new wire connector with a fusible link for just the alternator wire??
If you haven't done so already, disconnect the battery immediately!!!! That's just wrong...
You should purchase a new harness, but you need to investigate a couple things first.
You describe a connector behind the distributor C403 on drawing (Figure D page 7). You also show 2 fusible links (A & B) at the starter if both are true you have a second design or late production 1977.
Assuming, fusible link A is going to the generator like you say, where are you getting power to your headlight switch from? That should come from the cut fusible link B wire.
The purple wire on the S stud of solenoid is your ignition (manual trans clutch start) or (automatic trans neutral safety) switch wire.
You can click on the drawing, it should get a little bigger
The battery is indeed disconnected. To be clear, that bubba connection was heavily wrapped with electrical tape before this.
I don't know where the headlights are getting their power from right now. This is my first real dive into electrical on my car, so please bear with me. Basically, will I need to start peeling away the harness tape-wraps so I can expose the wiring to track where everything is going?? Some of the wiring in the overall engine harness looks much newer than other wiring. Below is a pic of the wire coming from the S-post on the solenoid to the connector behind the distributor. At this point, the only major electrical system that doesn't work is the heater/AC blower. All exterior and interior lights, dash lights, etc. are all working.
Is there an additional check I can do to verify my car is indeed a later production '77, just so I know I'm tracking the correct wiring diagram?? Looks like I need to purchase a diagram either way.
OK, so it looks like a 1st design or early build 1977, VIN 02287 through 27372. There were 2 early harnesses, manual trans and automatic trans.
The bad part both are a complete engine harness. You will also see a starter extension wire listed Scroll down to match your engine & extension harness LINK: https://www.lectriclimited.com/vehic...ke/21/model/65
So what I called the B fusible link that is cut on yours is not needed.
You will still have 2 fusible links but on the 1st design harness it will be located below the master cylinder, or in that area. Not as shown at Figure B of page 5.
Here is a link for the 1977 Corvette Electrical Troubleshooting Manual. Just number and save each photo in a folder and you will have all the pages. LINK:http://www.europeancorvette.com/html...l_diagrams.htm
1st design Power Distribution drawings are on pages 4 & 5
Hope this helps.
If you enlarge the engine harness photo of the lectric limited link you will see near the fusible link (Black Capsule large red wire) a black wire with an eyelet on the end. This is the main ground wire for blower motor. Should be bolted to the bell housing of transmission. May be one of the causes of the heater problem your having.
Thank you so much for all this help! Sorry for the delay, had an unexpected house project to get done this weekend. I'd rather be wrenching on the Vette......but....
My VIN is in the 19000's, so it's an early build. I had no idea there were early and later builds for this area. To clarify, my car is an Auto w/ A/C.
I will look at all those troubleshooting diagram papers and educate myself as much as I can. That looks like a great resource.
As for the Lectric Limited harnesses, I think I see the photo/option you are looking at, but that looks like the harness for Manual Transmission early model. The Automatic harness picture doesn't show the black ground wire with the eyelet......at least from what I can see. Maybe I don't see it or I'm looking at the wrong listing.
I actually do have a black ground coming down to the tranny housing and it appeared to be hooked up proper. That ground wire comes to the starter area along with the "alternator" hot wire in my photos. So, I'm not sure what exactly is going on. But, I will do my research with all you've provided. Thanks again!!
The black ground wire and eyelet is there on auto, manual, early & late harnesses. Trust me it's there you just don't see it. I can't verify earlier then 77 but later years also used the same grounding point.
If you want to try something heater fan motor related Insulate bubbas cable clamp wire connector and connect battery.
Look at page 15 of the 1977 electrical troubleshooting manual, check if you have a black wire and connector connected to the BLOWER GROUND TERMINAL seen at FIGURE B. This is your fan motor ground, needs to be there.
If so,
Without starting the car, ignition switch in the on position, fan speed in LO position and top slider control in OFF position do you hear the fan motor running? It was designed to run all the time to keep fresh air entering cabin, so it's normal. If it doesn't run, ignition switch OFF look at pages 16 & 17 of the troubleshooting manual. On page 16 you will see BLOWER RESISTORS on drawing, on page 17 you will see where it's located (on top of evaporator housing). Unplug the connector, unbolt it from the housing and you will see sets of resistor coils, make sure each end is connected and any of the coils are not burnt through.
Disconnect Battery when finished...
OK, I finally made time to get going on this. I hooked power up again and started checking the blower motor issue.
I verified the Blower Ground Terminal was hooked up. I did clean up the contacts at that location. I also checked the ground wire attached to the tranny housing. It is connected, but the wire connection with the eyelet had worn a bit. But, it was connected.
The blower does NOT run when the ignition is ON and slider control is in the "OFF" and fan is on "LO". I then cleaned up the contacts at all wire connectors on the Blower Relay and Blower Resistor. I looked at the Resistor Coils and they appeared all attached with no damage.
One good thing was that I tried the heater/AC controls again and I felt my blower run for the first time in the car! However, it would only run on the Max A/C setting or with the fan speed on HI. The other three fan speeds would not work on any other setting. I put a new fuse in the interior fuse box and verified I had 12 volts at that terminal.
I've been trying to get the Troubleshooting Guide figured out for a next step. Would it possibly be a faulty circuit in the Blower Relay?? Or, is it something in the Resistor?? I was also thinking I should verify the wire connector harness hook-ups are all in the proper slots. So.............here are pics of those.
Relay grounds and High Speed Relay Resistor connetor Other Relay connector
At this point, I'm a little stuck. Any additional direction is appreciated!!
OK, first photo, that connector 2 blacks and pink (C136) = connector number, you have an early build, mine are 2 blacks and a orange late build.
When you look at page 16 of the troubleshooting manual you will see the pink wire, CIRCUIT 988.
The connector in your third photo also goes to the HIGH SPEED BLOWER RELAY and is (C137) 3 wires Dk. Blue, Purple & Red.
Still on page 16,
When your HVAC controls upper slider is set at A/C MAX position or the fan speed switch is set to HI (CIRCUIT 988) it energizes (Powers) the HIGH SPEED BLOWER RELAY Coil, the relay contacts then change state from #12 Dk.Blue/#12 Purple to #10 Red/#12 Purple then directly to the blower motor, that bypasses the blower resistors (fan speed control).
So your heater fan works, but only under certain conditions.
Does your fan work if set to NORM A/C, VENT, HTR, or DEF positions and the fan switch is set to HI?
Does your fan work if set to NORM A/C, VENT, HTR, or DEF positions and the fan switch is set to any other fan speeds?2nd photo blower resistor connector.
2nd Photo Resistor Connector:
Wires, Brown, Lt.Green, Lt.Blue & Dk.Blue
Brown is direct from 25amp HEATER A/C FUSE. This bypasses the fan speed switch directly to the blower resistor Lo, Dk.Blue to blower motor, GM fresh air entering cabin thing.
Lt.Green from blower switch M1 to Med Lo blower resistor, Dk.Blue to blower motor.
Lt.Blue from blower switch M2 to Med HI blower resistor, Dk.Blue to blower motor.
Hope this helps....
Thanks again for sticking with me here. Now that I've stared at pages 15-17 for the last couple days, I'm starting to understand what you are explaining!
Does your fan work if set to NORM A/C, VENT, HTR, or DEF positions and the fan switch is set to HI?
Yes, I did test that yesterday
Does your fan work if set to NORM A/C, VENT, HTR, or DEF positions and the fan switch is set to any other fan speeds?
No, all fan speeds below HI do not work, including the blower not working at the OFF slider position with the Ignition "ON".
So, the issue almost has to be in the resistor OR is it possible the blower switch is an issue?? Or, could the "Drk. Blue to Purple" single circuit of the Relay be bad?? I would think that would be least likely because of the Relay working for the HI-speed settings.
Maybe I'm at the point where I just need to do voltage checks from the blower switch all the way to the "C137" relay point??
If you unplug & unbolt the blower relay, I think there are little metal tabs that can be bent up so you can pull the cover off, if so try cleaning up the contacts inside. "0" expense..... "Or, could the "Drk. Blue to Purple" single circuit of the Relay be bad?" This is another set of contacts (all fan speeds except HI) inside the relay. May need cleaning.
Just now, I did some voltage testing at the resistor and at the purple wire connector at the blower motor (pg. 15 Figure B, C104) Obviously I have 12 volts at C104 on Max A/C and HI fan, as the blower is working then.
I also checked the Brown wire at the Resistor connector and have 12 volts there with the key ON, panel slider at OFF and the blower switch at LO. There is also 12 volts on the dark blue wire of the resistor (if I have the progression correct) Going further, I still have 12 volts on that setting at C104, as well as the wire connector that plugs right at the terminal on the body of the blower motor. That would tell me the fan should be running all the time on that "Cabin Air" bypass circuit with just the ignition ON. So, would that indicate the blower motor is actually the problem?? Or is it still a bad ground connection at the blower or the tranny mount??
I may have to take that tranny ground off and see what kind of condition it's in.
Took the tranny ground off, cleaned it up and it looked well enough. Hooked it back up and still no changes or progress from before.
Took apart the relay. I do see an area that looked to take on a lot of heat and is burned. Hopefully you can see it in the pics. I did a basic continuity (sound beeper) test with my multimeter on the three prong connector posts. I got continuity from the purple wire post and red wire post. But, I did NOT get it with the dark blue to purple wire post. I looked really close at the contact points for that connection and it looks like they are disfigured and not flush with each other on contact.
This is strange, because I still got 12 volts at the blower motor from that circuit.
The black you see is from the relay coil getting hot may be bad, but mine probably looks the same.
I do see some what looks like carbon between the contacts (Points) 1st photo. Make sure both sides are nice and clean the best you can.
Check power at the 2 wire connector (between blacks & pink wire) Check both, A/C MAX and OFF slider positions. What has 12vdc at plug?
Testing the relay coil, Ignition still on A/C MAX with the cover still off plug in the 2 black and pink wire connector only.
Watch what the contacts do when it powers on & off, plugged in & unplugged repeatedly.
At the 5:07 mark in the video this is what your contacts should be doing, power on, power off.
I completely missed your post #13
So you have voltage like you should at the resistor so let's rule that out as defective for now. You have HI speed fan only and continuity at the relay between RED and Purple relay contacts. This morning I looked at my 1977 blower relay and this is what I found.
With ignition switch on, slider and fan speed switch off blower motor runs in low speed. The blower relay coil is NOT energized, so the power to the blower motor is going through the N/C contacts #1 & #2 page.
Slide to MAX AC or any other function and fan speed switch at HI the relay coil does energize switching contacts to #1 & #3.
So your relay contacts are frozen between contacts #1 & #3 or it's not the correct relay.
Great pics you put up, as well as the Willcox video!
Tonight, I did the relay test with the relay exposed and both connectors hooked up. With the ignition ON and Slider in the OFF position, the contacts stay in the position for #1 & #2 to contact, but the fan does not run. At Max A/C or HI fan speed control setting, the contacts "click" and switch to the #1 & #3 position, so the fan then starts running on high speed. I could see them locked down and then return to the #1 & #2 position when I put the slider back to OFF or HI fan speed back to LO.
What's confuses me is that I still have 12 volts at the blower motor when the #1 & #2 position is "engaged" at the relay, even though the blower is not running. I took a really close look at the contact points on the relay for #1 & #2 and I can't imagine those surfaces are good. There is contact, but hardly anything. Being as careful as I could, I tried bending/manipulating the arm that houses the contact in position #1 & #2 to see if I could get any reaction from the blower at the "OFF" slider setting, but didn't get anything.
Contact is angled and not flush in the #1 & #2 setting.
Here's where my inexperience on electrical comes in...............but............is it amperage that determines the speed of the blower fan?? If so, could those poor contacts be allowing voltage to pass to the blower, but not have enough amps to actually make it move??? I'm guessing a new relay is my next step, but let me know what you think.
Thanks again, this has been a bit frustrating but a great learning experience for me. I'm so grateful for your help and details.
Yes the contacts look a little askew......
Ignition on, test the #12 Dk.Blue wire to ground at the 3 wire relay plug, do you get 12vdc when slider is at NORM A/C, VENT, HTR, or DEF positions and the fan switch is set to all but HI speed?
Lets say YES (like I think you said above but motor not running) then you know you have power through the blower resistor all functions above and fan speeds.
I don't know where you shop for auto parts and if you want to try a new relay here are some part numbers, shop around some are around $10.00 + shipping. Delco brand may be higher, Standard is a good brand also. If you find a old stock relay made in USA the quality will be superior.
GM #3989214
ACDelco #15-8169
Standard or Standard Plus #RY-12
Four Seasons #35767
Below is a pic of the underside of the relay.............
Ignition on, test the #12 Dk.Blue wire to ground at the 3 wire relay plug, do you get 12vdc when slider is at NORM A/C, VENT, HTR, or DEF positions and the fan switch is set to all but HI speed?- Yes, that is what I found this morning. I don't know if this makes a difference, but I still have 12 volts at #12 Drk Blue when the slider is at MAX A/C as well. The Pink #4 terminal wire also shows 12 volts and then 0 volts when I move the slider off of MAX A/C.
We have a NAPA and O'Reillys here. NAPA has an Echlin brand relay and O'Reillys has an AC Delco "Multi Purpose Relay" that look to be the same. So, I will probably go and order one today and see what happens. Thanks again!
Looking at page 16 drawing the #12 Dk.Blue wire out of the resistor to the relay will have 12vdc when the ignition is on.
The Brown wire from the 25 amp Heater/AC fuse to the resistor is always hot with ignition on. Fresh Air Entering Cabin thingy...
Remember, once you select A/C MAX or fan speed HI, the relay coil energizes changing the state of the relay contacts taking the Dk.Blue wire out of the path to the motor.
For reference, not sure what the Echlin contacts are rated at but Napa's Mileage Plus Brand contacts are rated: N.O. Terminals 1-3 At 20 Amp,
N.C. Terminals 1-2 At 12 Amp,
