dembo

Hello Everyone,
First of all I would like to say thanks to Roger for putting up with me and my pesky questions during the testing. I hope I'm almost there Roger, I wouldn't have made it this far without your help, There is no way I can every repay you, unless I visit the states next summer !

I thought I just might post this and hope it vould be of some help to someone going through a restoration process or has electrical issues. Sometimes it might be a bizarre read due to my English & because it's a mix of mail messages combined with text added.
Enjoy :
Car :
1974, Coupe, 350 L48 automatic, no electric windows, no rear defogger, AC.

Whats new
TH700R4
350HO 330 hp crate engine, deluxe. (serpentine kit, with AC compressor, CS130 105A alternator and HEI distributor
Electric fan (fan itself not connected)
New AC harness, Interior harness + fuse box, rear harness, front harness, engine harness (in short all new electric harnesses)
Nevernight (from speeddirect) xenon light harness
Led bulb lights for front and rear side markers, stop and rear lights and license plate lights (original housing, just the bulb is a led version)
Mandatory rear fog led (high bright row of leds)
Hydraboost
Steeroids steering
Radio + sub + kick panel speakers + electrical antenna + replacement dash speakers
Powerjection III returnless (not yet installed).
Shifter conversion bracket kit (3 speed to overdrive).
All new courtesy switches, door ajar switches, ignition switch, ignition lock, neutral safety switch, horn relay, turn signal electronic flasher, rear storage compartment switch, directional signal switch, brake switch (cruise control type 4 lugs 2 contacts 1 normal open for brake lights & 1 normal closed for the lockup), wiper switch, light switch, heater blower switch, A/C relay, heater resistor, hazard flasher, key warning switch
Blower motor
All new gauges : ammeter, fuel, oil pressure, clock, temp
Replacement tach from a 1975 with new tach board from Ernie + capacitor (between HEI & tach)
Wiper motor & mechanical washer pump
Gas tank & sending unit
New 3point seat belts, identical as original except the buckles have no contacts in them
Replacement seats, so no seat switches
Replacement horn (grounded through it’s mounting bracket)

Whats old
Key warning buzzer
12 brown capacitor (near ignition switch)
Seat belt warning buzzer
Parking brake alarm switch (on handbrake) (20gray)
Anti theft flasher
Anti theft relay
Interlock relay & Seat belt warning relay
Cigarette lighter housing

What was already removed by PO or broken
Time delay relay (in engine compartment) missing
Starter interlock override relay (in engine compartment) missing, the car started before the resto
Anti theft horn
Sequencing module (above the driver rear wheel well behind carpet)

What did I remove or is unplugged
In engine compartment :
20 yellow resistor wire from starter & 20 black/pink print (which used to be connected to the coil are taped together and not connected. Yellow resistor is also not connected to starter, which has only 2 lugs.
Idle stop solenoid (18 dk grn/18 tan) & vac advance solenoid (20 dk grn/20 dk blu) not connected
Anti theft switch hood (18blk / 18 wht)
Hood air door solenoid (18blk / 18 tan)
Anti theft switch (14 orn / 14 pink)
Anti theft warning switch (18 wht / 18 blk)
TCS transmission switch (18 blk)
Transmission solenoid (18 orn)
Transmission kickdown switch exterior side (18 tan – 18 tan / 18 orn – 18 orn)
AC compressor switch (16 dk grn / 14 blk)

In interior space :
Hood air door control switch (on gas pedal) (18 tan / 18 tan)
RH seat belt buckle switch (18 blk / 18 gray-wht)
RH seat switch (18 blk / 18 gray)
LH seat belt buckle switch (18 blk / 18 tan-blk)
LH seat switch (18 blk / 18 yel)
Radio convector

The Grounds :
Everywhere I touch metal and the volt meter is connected to the neg battery cable in the rear tray I have continuity.

1) Battery cable to chassis. (there is a star washer underneath the eye connection)



2) Driver side on frame rail (just in front of gas tank) ground wire (16 blk) from rear harness + ground wire coming from led fog light



3) Ground to sender unit (18 blk).


4) Ground wire from chassis to block Please note that this is not the routing as mentioned in the AIM. It should go from the motor mount support chassis side to a bolt which connects the starter to the block!)



5) Ground wire to bell housing (14 blk), the one commonly mistaken to be connected to the starter.



6) Above the horn and vac relays for the headlights (near the tip of the hood you can see the radiator support brace) ground cable from front wire harness + ground cable from nevernight xenon lamp harness



7. Ground strap from front driver body mount to bird cage.



8. ground wire from engine harness to wiper motor.



9. one connected to the radiator support. I can’t remember if it comes from the nevernight harness, or the foreward lamp harness. The picture is taken in between the open hood and rad support



11. other grounds are : 1 to speedo, 1 to tach, 1 double wire to heater control, 1 to birdcage (above LH kick panel), door ajar switch bracket to birdcage, one on each side. (sorry no pictures)

This is a view on the alternator.
The nevernight harness power cable is connected directly to the alternator stud as is the power cable to the cooling fan. The 10 red coming from the junction block (engine harness) is connected to a threaded stud on the nevernight harness power cable. The black ground is connected to the alternator mounting bracket.
The ‘signal?’ wires from the original harness are connected by a replacement cable. As there is no battery light I chose this one and I think it’s a resistor wire. (If you do have a bat light, there is another type available).



On the pictures below you can see the wiring of the add –on products like stereo, electric fan controller etc.
All this wiring was done according the guides which came with it. I only know the power to the lights comes directly from the alternator, the original forward light harness connectors plug into the relays that came with the kit and the are just triggers.
All the accessories get their power from the painless cirkit boss. The power comes directly from the battery through a circuit breaker with a heavy gauge wire.
The constant 12V supplies (radio, amp) is supplied by a heavy gauge wire directly from the battery, through a 40A fuse.
All grounds for these extra items come together on a junction block inside the battery tray. A heavy gauge wire connects the terminal block to the battery.
The two heavy gauge + wires and the heavy gauge – cable where NOT connected during the first test.
The only thing which is connected to the original harness is a toggle switch which turns the led rear fog light on and off. I used the radio wires, yellow as power and black as ground. The grey wire is connected to the stereo to dim the lights.
The 12V wire from the dizzy I tapped directly after the starter switch, with a scotch lock. I tried to simplify the main circuit as shown on second picture below.
Junction blocks inside the battery tray

Cirkit boss inside the jack storage bin

Trigger for cirkit boss

Schematic :

Starter harness with extra cable for HEI


Below is a picture of how the wires are connected to the starter :
The battery + cable and the 12 red on the same lug, the purple on the remaining lug and the yellow not connected.


The test

The LH dash pad is in, everything connected and so is the instrument cluster with everything connected. I don’t think the plugs to the gauges can be inverted. Lighter is connected + it’s light, the PRND321 lamp, the handbrake switch, in short all the connections how it should be, and checked with AIM & wiring diagram. The wiper switch was NOT connected. The washer pump leads where not connected and I payed attention they didn’t touch anything iron.
I bought a 12V supply protected by a 10A fuse. (the ones used to test car stereos). Connected – to the neg battery cable in the rear tray. Then touched the + wire to the + battery cable.
These are the things that happened :
• Immediately the key buzzer came on, key out of contact, driver door open. Pressed the courtesy switch and the buzzer did not stop. Put the key in did not stop. With key in and pressing the courtesy switch, did not stop.
• Meanwhile the oil pressure gauge turned COUNTERCLOCK wise to maximum (turned very slow)
• The courtesy lamps did not come on even with the both doors open and rear interior lamp isn’t coming on either
• The clock wasn’t working
• The gauge lights come on, although I can’t remember if they came on with the key in off position or in run position. I think in the off position.
• Turning the dimmer switch did not turn on the courtesy lights
• The door ajar light came on with key in on position but did not turn off with passenger door closed and pressing the driver side switch.
• I also noticed the wiper motor turning very slowely.
• When connecting the power supply for a longer period a typical burned smell was noticeable.

After the test check
I noticed the neutral safety switch was out of alignment, so this was corrected.
The crtsy fuse was blown.
I disconnected the wiper, retest, but all the above symptoms happened again, except the wiper motor turning.
I removed the gauge cluster and tested every gauge but the oil gauge and they all function, the clock as well. (test found on the forum).
Ordered a new key buzzer switch
Different courtesy light switches
I pulled the turn signal connector off and measured continuity between the two pins and it has, so I assume the key buzzer is not set up right (found the two pins with Lars’s pages).

As I’m more mechanically inclined and had no clue how to test it’s time to check in with the specialists (Roger).
Issue 1 : First of all it was strange that the crtsy fuse blew (25A) instead of the 10A fuse on the power supply …
So a new fuse was put in and then ran the most simple test with a test light

Sure enough the light came on. Time to start removing fuses and perform this test. Logically I took the crtsy fuse out first : test light went out. Alright ! circuit with problems identified.
From the beginning I had issues with the courtesy light switches. I used the correct style for my year : the ones with use the small terminals and a round pin on the switch to isolate them.. I always thought they could come loose and connect to each other. Or they might be in contact with the speaker housing in the kick panel.

The new ones I ordered are the spade type which I felt more secure with. The plastic isolator between the two spades is also larger. To be sure I taped both to avoid they would make contact with the speaker housing.
Before running another test I took the shifter console & the gauge cluster out again to minimize other issues.
So new courtesy switches in, doors closed, light switch not turned completely to the left I hooked the test light to the battery and the light stayed out = issue in courtesy light circuit solved . Beware, the spade type switches are shorter, so to make sure they get depressed when the door is closed, I will use 3M bump on’s. Not the most elegant solution, but hey they used them for the 69 to 72 ? Vettes.


Issue 2 : The key buzzer. After doing all the checks explained in the chassis manual and on Lars’s papers it keeps on buzzing 24/7.
This test convinced us that either something is wrong with the buzzer switch or with the turn signal switch :

With the key out there should no continuity between the two spades. This was the case but one of the two had continuity to ground !
Time to dig into the upper steering column and reveal the switch. First of all the new buzzer switch was put in and tested according to the chassis manual (open & closed gap). While the turn signal switch was unbolted I did the same test between the two pins of the harmonica connector steering column side. Of course there is no continuity between the two as the buzzer switch has no contact to the TS switch. BUT the continuity to ground between one of the two lugs was gone ! Bolt the TSS back in and the continuity to ground appears again. This lead us to believe either a wire gets pinched or the TSS is making metal contact to the steering column. The new TSS came in yesterday so I’ll try to put it in next week and hope it will resolve the issue as there is no real evidence a wire gets pinched on the old one.
This is a standard column and from what I have seen there is no isolator between the TSS & the steering column, only for the T&T column, so I presume I’m not forgetting anything.

Issue 3 : the RH side marker is dim, the RH turn signal indicator glows and the RH front park lamp doesn’t work. This turned out to be the most time consuming issue.
First test to do was run a long wire from the Rh front marker casing directly to the battery. This test will show if the ground in this circuit is ok or not. If all 3 issues go away then it’s most likely the ground connection in between the headlamps near the horn as shown in the pictures before (or a broken wire …).
In my case it didn’t resolve anything. Ialready removed the led bulbs and replaced them with candescent bulbs to eliminate them as a probable cause but it made no difference. As all the rear lights seemed to function correctly the next best step was to remove the bulbs out of the trouble area. I first took out the front RH park lamp and while fiddling with it I noticed the side marker was sometimes glowing at normal intensity.Bulb out : et voila! The side marker glows at normal intensity, the turn signal indicator is off. The problem where the two contacts at the bottom of the casing. One of the two was actually twisted and completely pushed back in the housing. Bending it back resolved all the issues. Bare in mind this extension harness is completely new….
For now only the rear bulbs are replaced by led bulbs, because I like the intensity and the solid state. When I tried the front ones, they didn’t came on anymore. I probably need to add a load ballast but it can wait.

Issue 5 : The reverse lights where on 24/7 with the key in ON. As I wrote before, the NSS was adjusted correctly and tested before putting the shifter in the car. The 74 cars do have some extra wiring going to the NSS and its directly related to the seat belt interlock system. The pink/light green from the neutral safety switch is connected to the interior wiring harness (although they switch color
when plugged in but I assume this doesn't make much difference). I then checked the wiring diagram again and noticed the seat belt warning relay. I checked it in the AIM and it should be next to the
handbrake. Well mine is of course missing. I'ts connected by a 3 spade connector with wire colors ppl/yel, yellow, pink and a second connector tan, coming from the handbrake. The yellow & pink connector should also come into the picture here. If you look at the photo you see on top
the connector ppl/yel, pink, pink+pink and below the connector yellow, pink. One of the pink wires from the top connector also goes to the backup light connector (along with another pink & the lt grn) so i figured, I don't have the seat belt thingy and kept the two connectors unplugged (the ones in the picture). Then connected the battery, put the ignition in ON position, gear lever in park : backup lights did not come on. Put the gear selector in Reverse and they came on! Issue solved!
Comment from Roger : The green print about the seat belt and reverse lights. My guess is your fine there. Usually in this belt interlock system if the interlock relay in the console is plugged in and all other wires are unplugged the system works. Reason for this is the relay is in a normally closed state,grounding from the seat belt passenger weight sensors is what opens the contacts to interrupt the starter.

As this work is related to the starting of the car, remember the clip replacing the starter interlock override relay from before? Well I didn’t feel quite safe with this solution and bought a used override relay on ebay. Opened it up and did what vetfxr did to his relay : solder a heavy gauge wire in between the contacts coming from the purple & green/black.
http://home.comcast.net/~vettfixr/page17.htm
Le moment supreme : turn the key to run and oooh yeah it cranked !

Issue 6 : Continue with the center console & gauge cluster. First test indicated by Roger : use the 12V supply to test the lighter (dumb me didn’t even think of that). The housing itself is old, the removable part is new. Not that I’m going to smoke in the car, I just like everything to work as it should and work it sure did. So both where put back into the car. Before I rechecked all the grounds on the gauge cluster as indicated on the picture.

Note these are all new AC delco gauges which don’t require the resistor wires. All grounds checked out fine.
With everything assembled it was time to connect the battery. Clock works, batt moves negative when a power hungry item is turned on (like headlamps), temp & fuel gauge zero themselves, lights on the shifter console go on, blower motor speed functions as it should, except the oil gauge. This pegs to maximum but counter clockwise…

And another tip from Roger. The dark blue wire from the oil pressure sensor is removed and the lug (wire side) is grounded directly to the battery -. Turn key to on : the gauge went to zero. It means that the pressure sensor has no contact to ground (the engine block). I checked both the temp & oil sender and they where both put in with a lot of Teflon tape which is most likely the reason. Bought some permatex liquid thread sealer and will take them both out probably next week.

Issue 7 : The wiper motor. After all the previous test I assembled the metal bracket to the gauge cluster. Although the wiper motor turns & parks it’s not functioning as it should. When you push (washer and low speed should go on) nothing really happens. When you slide it to low speed the motor actually turns on high speed. When you slide it to high speed the motor parks. Turns out the switch itself (new …) is a bit iffy. The little lever is very loose in the switch, so you actually have no clue what position you’re in. when its somewhere in between off and low, the motor goes in low speed, when you position it somewhere between low and high it goes in high speed…. New switch is on it’s way made from GM tooling … I hope it’s a bit more solid then the one I have now.

So far all the issues I had and how they got resolved.
Thanks for reading,
Nick

427SIXPACK

NOW THATS INFORMATIVE !!!!

W O W !!!

Alan 71

Hi d,
That really is a useful post. Thanks for taking the time to put it together, it must have been quite an effort.
I agree that Roger does have the answers to lots of questions.
Good Luck and Thanks Again!
Regards,
Alan

moose8793

Excellent work
Thanks for sharing

dembo

My pleasure, only 2 hours Alan
Nick

...Roger...

Wow that's the longest 1st post I've ever seen.
Glad you got it all worked out and I was more than happy to help.

MyRed69

Looking good Nick, guess I'll need to take another trip out there to see. It sounds like you have made a lot of progress. Heading to Berlin next month, too bad it's such a long drive to your place.

srs244

and i agree with alan that is really informative. thanks for taking the time to post it up.

C3batmobile

Thanks for this.

sly vette

Your gratitude for the help given you is evident in the amount of effort you put into your post.
Great job!
Talk about paying it forward!!!

thegavel

AWESOME work, dembo.
Thanks.

dembo

Its the least I could do, I hope it could help someone in the future.
The turn signal switch was the cause for the key buzzer to ting continiously, the new one resolved jthis although the connector didn't fit the harness luckely the 'old new' one did so it was swapped out.
The only issue still is the oil gauge pegged to +80 when the sender wire is on. Take it off and ground it : goes to zero. Send a mail to willcox customer service if their oem sender would be the solution. Hope they answer quickly so I can order
Regards
Nick

dembo

Update on the pressure sender which I got from Willcox today ()
Oil gauge goes to zero with key on & this sender but my block is 1/4", the sender is 1/8" so now I've got to wait for a NPT reducer which you can't find here ...
The sender which comes with a GM crate engine is the idiot light style
So far all issues seem to be resolved
I only got one thing to say :

THANKS ROGER !!!
Regards,
Nick

...Roger...

My pleasure Nick.

So the sender you sent me a pic of was an idiot light sensor ? You might want to post a pic of it so others can see and be aware of. If I remember right it looked like a gauge type but was missing the hex area just under the electrical spade.

dembo

Sure :
Idiot type sender with 1/4 NPT thread and a threaded end with nut
Regards,
Nick

crsallen77

Im having alot of start problems with my 74 too, ive been reading for HOURS on here and doing things to rule out the obvious things. Where is the location of this seatbelt interlock? It seems as if they (whoever jerry rigged my electrical system in the past) tried to bypass it some point. Also the guy that cut me an ignition key did something to my steering column as now the left turn signal indication in the dash stays lit all the time.

7T1vette

Great write-up.

One observation: I've always seen the ground wire on the right side of the engine run from an engine motor mount bolt directly to the forward starter mounting bolt. That way, starting current is fed directly through the starter frame instead of going though the cast iron block. It probably won't make a big difference, but thought I would mention it.

You've made lots of progress on a difficult task. Congrats!

Richard Daugird

This will come in handy as a reference when installing my new stereo and chasing down why my new alternator isn't charging my new battery.

OOPS I just realized this is five years old! Oh well maybe it will help someone else who is new like me and missed it.

dembo

Glad it's still usefull to some
Nick

Vogast

Dembo, is there a chance to load the pictures again? This an extremely useful topic and the pictures are gone from the servers. Or I can PM. Thanks