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1985 Celica Supra
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Discussion Starter · #1 ·
This is probably a pretty simple wiring thing that I messed up but I’m not sure. The previous owner had electric fans with a whole mess of wiring that weren’t really doing the job so I ordered the stock fan clutch and installed it. After making sure the car was running fine I disconnected the fan and all of its wiring. It had two wires running into the positive terminal of the battery that connected to a relay. After detaching these the car doesn’t start. Dash will light up but when I turn the key there’s just a click. I’m guessing I just made a beginner mistake or something but I have no idea what it would be.
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That big wire in the center runs down to the starter and it sure looks like a lot of corrosion
 

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Discussion Starter · #3 ·
As an update the ground that was connect to the car was all corroded so I cut it off and reconnected it and the a bunch of yellow smoke came out and the wire fried
 

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Yeah fix all those battery cables first off. Remove the battery from the car, give yourself space to properly clean those cables up, and find the issue. We can't fix it from here. As stated above your battery cables look all kinds of corroded, the one on the far right looks to be crispy and then covered in electrical tape as a temp fix, every single connection looks rusty to me. Clean it all, trace it all to make sure it's going where expected, and so on. Also get a battery tie down of some kind, flopping around battery is going to break your connectors and possibly cause a fire.

If you saw wires like that in your house, saw smoke, would you reconnect the power until you figured it out? You're trying to troubleshoot an internal combustion engine here, and the electricals are dickered within squirting reach of your probably crispy old fuel injector o-rings and who knows how old fuel lines/filter. I could be wrong about the state of things, but judging by your smashed up vacuum switching valve with no hoses in the area, missing headlight motor covers, i'm gonna guess this thing has had a rough past.
 

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As an update the ground that was connect to the car was all corroded so I cut it off and reconnected it and the a bunch of yellow smoke came out and the wire fried
Post some photos of this ground wire, hope you didn't connect it to anything on +12v side of starter circuit. You've got some problems (at least 2 or 3). Car not starting is not problem, it's only symptom or result of real problem. Which are issues listed below. Fix all of them and car will automatically start.

I. BATTERY VOLTAGE
Measure voltage directly at battery terminals. Voltage = ???

II. INCORRECT WIRING CONNECTIONS
You disconnected TWO wires going to positive terminal. Maybe only one of them was for fans and other for starter circuit? Get proper EWD and trace every wire in starter-circuit end-to-end. Make sure BOTH ends of every wire is connected to proper component.

III. POOR QUALITY WIRING
Wires carry current on surface of wire. That's why you want stranded wires to increase surface-area. But if surface is corroded...



You'll end up with high-resistance, heat and insufficient conductivity. All wiring should have following (yours is missing 2 out of 3):

mechanical strength - crimped or tied knot
electrical conductivity - soldered
weather-proofing - sealed to prevent corrosion

It's done this way in pro-motorsports, aerospace and military applications for performance, durability and reliability. Here's how to properly make battery-cables (use lugs rather than thin ring-terminals):



It's crimped, soldered and sealed with adhesive heat-shrink wrapped at end. Then use military-style zinc battery-terminal clamps for conductivity and corrosion-resistance. I used to make heavy-duty starter and headlight harness with 50-yr warranty. Been 25-yrs now and not single one has come back. Occasionally they come up on eBay selling for twice what I sold them for. Many people even remove them from old car to transfer to new car.




Remember, there's never enough time to do it right 1st time around. But there's always time to do it again! Often on side of road in total darkness and rain.
 

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Discussion Starter · #6 ·
Ok so even though all of the wires are all corroded the thing was starting fine up until I took the fan wiring, so while I’m sure that’s an issue as well I get the sense that there has to be something else up. I’m super new to this so how do you guys recommend to clean the cable? Or should I just replace the whole thing? After looking into it a little bit more I realized that the negative cable doesn’t have any ground connected to the fender where it typically would so maybe that’s the problem? Sorry for my inexperience but could somebody possibly explain to me what each of the cables coming off of the battery is? Like what are the extra two wires connecting to the positive terminal? And is it necessary to have a the battery grounded to the fender as well as the engine with the main black cable?
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Discussion Starter · #7 ·
I’m kind of guessing not having that secondary ground wire to the fender is the issue right?
 

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Yes, it will not start with that ground wire missing
 

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Sorry for my inexperience but could somebody possibly explain to me what each of the cables coming off of the battery is? Like what are the extra two wires connecting to the positive terminal?
I’m kind of guessing not having that secondary ground wire to the fender is the issue right?
Wait... you messed with positive terminal wires and caused it to not start. Now you're messing with ground wires?

I think it comes down to what kind of solution you want.

1. permanent fix-it-once never have to worry about it ever again. This solution has already been presented. You need to verify all wiring is connected properly. And replace all battery-clamps and cables with higher-quality components. At least to OEM-spec, even better to improve on it. Here's link to EWD

2. quick fix-it-now to get back on road again, but have to bandage and duct-tape it monthly to keep it coughing along. This will only cause car to degrade on downward spiral until it takes too much time, money and effort to keep alive and ends up in junkyard.

I'm not going to help you with #2 and cause destruction of another rare MK2. Fix it right or take it to someone to fix properly. Just because it "runs just fine" doesn't mean it's working properly or will continue to work long-term.
 

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Those battery clamps like you're using suck and really susceptible to not making good connections. The fact that the solenoid clicks and the rest of the car works suggests your aren't getting good power to the starter. Same problem you have with a dead battery. The 5M starter is 1.4kW which is 116 amps. If you're clamping down on a corroded piece of wire and battery clamp the resistance to current it very high and you're not going to get 116A. You probably removed or loosened those clamp screws and the wire shifted slightly to a corroded spot.
 

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Discussion Starter · #11 ·
Wait... you messed with positive terminal wires and caused it to not start. Now you're messing with ground wires?

I think it comes down to what kind of solution you want.

1. permanent fix-it-once never have to worry about it ever again. This solution has already been presented. You need to verify all wiring is connected properly. And replace all battery-clamps and cables with higher-quality components. At least to OEM-spec, even better to improve on it. Here's link to EWD

2. quick fix-it-now to get back on road again, but have to bandage and duct-tape it monthly to keep it coughing along. This will only cause car to degrade on downward spiral until it takes too much time, money and effort to keep alive and ends up in junkyard.

I'm not going to help you with #2 and cause destruction of another rare MK2. Fix it right or take it to someone to fix properly. Just because it "runs just fine" doesn't mean it's working properly or will continue to work long-term.
Ok so I’m not actually driving the car around on a regular basis I’m just driving it around my neighborhood occasionally to test whenever I install something new which is why I’d like a temporary fix for now so I don’t have to push the thing up my driveway. And as far as the two wires I removed one was connected directly to the relay which connected to the fans as well as a ground on the frame. The other one was connected directly to a switch inside the vehicle to turn the fans on and off. So as far as I know that shouldn’t have affected anything starting wise but correct me if I’m wrong because I definitely could be. The two remaining wires on the positive terminal other than the main big one connect into the wiring harness. Then on the negative side I only see the main negative cable connected to the engine block with nothing connecting to the fender. How should I attach a new ground wire to the fender? Like does gauge matter and do I just bunch the wiring under one of the screws on the negative terminal? Also what’s the best way to clean the wiring I have to maintain better connections? And as far as long term fixes how expensive would it be to replace all of the wiring for the battery and how much skill would it take? Like is it something I could do with my limited knowledge?
 

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As an update the ground that was connect to the car was all corroded so I cut it off and reconnected it and the a bunch of yellow smoke came out and the wire fried
How did you cut off and reconnect? To same corroded clamp on negative terminal?

And as far as the two wires I removed one was connected directly to the relay which connected to the fans as well as a ground on the frame. The other one was connected directly to a switch inside the vehicle to turn the fans on and off. So as far as I know that shouldn’t have affected anything starting wise but correct me if I’m wrong because I definitely could be.
Be extremely careful about tracing cable connections and where their end-points connect. Let me see if I understand the fan-circuit you removed:

+12v -> relay -> fan
+12v -> switch -> relay -> fan
-gnd -> fan

Removing these would do nothing to cause car to not start. As SilverMk2 mentioned, in process of removing fan wiring, you may have disturbed battery-terminal connections which resulted in worse connection through corrosion. Again, real fix is to replace all corroded battery-clamps and cables with better-than-OEM components.

The two remaining wires on the positive terminal other than the main big one connect into the wiring harness. Then on the negative side I only see the main negative cable connected to the engine block with nothing connecting to the fender. How should I attach a new ground wire to the fender? Like does gauge matter and do I just bunch the wiring under one of the screws on the negative terminal? Also what’s the best way to clean the wiring I have to maintain better connections? And as far as long term fixes how expensive would it be to replace all of the wiring for the battery and how much skill would it take? Like is it something I could do with my limited knowledge?
Not worth cleaning as there's too much corrosion and it's crept down entire length of cable giving it black/green cable disease. Best to replace; quick and easy.

1. replace battery-terminal clamps with corrosion-free clamps. Make sure your battery-terminals are not damaged and have proper diameter to fit. These don't bend like lead clamps. DO NOT overtighten! Shim battery-post if needed.

2. replace battery ground-cable to fender. What length was cable that fried? Replace with pre-made 2ga cable. Get 5/16" end to fit new battery-clamps and 1/4" end to fit fender bolt (remove that old ring-terminal where original cable was cut off).

3. replace main +12v power line to starter. Measure length end-to-end and get pre-made 2ga cable. Probably 5/16" lugs on both ends.

4. replace other two +12v cable-ends. These go to headlight-motors and rest of wiring-harness (ECU, injectors, dash, etc.). Remove crimped ring-terminals and clean off harness wire-ends. Use OxGard to remove corrosion, you may be able to save these harness wires. Then crimp on solder-lug, solder and seal with adhesive heat-shrink wrap.
 

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Discussion Starter · #13 ·
Did steps one and two so far and the car is starting again. Gonna start on the rest over the next few days, thank you for all the help!
 
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