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Help needed from 7M swappers - no spark

3K views 16 replies 8 participants last post by  SilverMk2 
#1 ·
Well I got all the wiring done (I thought) gave her a crank and no spark. Plenty of fuel though :) The other weird thing is my voltmeter light and brake light are on even with the ignition off and the key out! I have the diagrams but at this point when I look at them I just get a migraine. I've double checked a lot of connections but I'm not sure what needs to be corrected. Any suggestions are appreciated and will be utilized. I know there are a whole big bunch of other 7M peeps out there so help a brother out. Somebody out there has to be better at this wiring thing than me :)
BTW the car in question is an '82 5spd and the donor parts are from an '88 5spd with ABS.

Thanks,
 
#3 ·
Thanks for the suggestion. I thought that tiny little cracked ground on the coil pack plate looked suspect but I ran a new ground and nothing. But still a good thing to replace. How's your 7MGTE swap coming?

P.S. It's pretty sad when the only reply I get on a MK2 forum is from a Cressida guy :( (not meant as a knock to you Thermactor)
 
#4 ·
Paid for the motor and shipping, have reached a critical low point in my bank account balance, waiting for next paycheck to pay the $75 extra for the guy sending the motor with an unloading truck (I have to do the swap out in the parking lot, it's going to be hairy for sure!) Also getting a 3.73 LSD, but I'll have to swap the housings over (maybe have a shop do it for me).

So you're not getting spark? Have you checked all the wires going to the coil packs? Are you getting voltage at the "+" leads? Something you say that worries me:
The other weird thing is my voltmeter light and brake light are on even with the ignition off and the key out.
If I were you, I might go back and look at how I wired the motor up to the car's body harness. Something isn't right, methinks. Have you tried Jim King's MkII conversion site?http://www.celicasupra.com/7mgte/Wiring.html
Just a hunch. Other than that I'd read the MkIII TSRM to try to chase the problem down. Good luck man.
 
#5 ·
Thermactor said:
So you're not getting spark? Have you checked all the wires going to the coil packs? Are you getting voltage at the "+" leads? Something you say that worries me:
The other weird thing is my voltmeter light and brake light are on even with the ignition off and the key out.
If I were you, I might go back and look at how I wired the motor up to the car's body harness. Something isn't right, methinks. Have you tried Jim King's MkII conversion site?http://www.celicasupra.com/7mgte/Wiring.html
Just a hunch. Other than that I'd read the MkIII TSRM to try to chase the problem down. Good luck man.
I don't like seeing this either.If those lights are on,you definately have at least one wire wrong.Have never done an 82 yet,so I'm not sure of all the proper pin-outs,no help there,and I don't have an 82 electrical manual here :( YET .

Recheck all your wiring,pin by pin.Take your time,unfortunately,thats what it's going to take.
Good luck,let us know whats going on,will try to help where I can.
 
#6 ·
Junkie said:
Recheck all your wiring,pin by pin.Take your time,unfortunately,thats what it's going to take.
Yeah that's what I'm doing but unfortunately I have no way to confirm that what I'm double checking was right in the first place. I have the wiring diagrams for both 82 and 88 but it only helps so much. I had hoped that someone familiar with 7M swap wiring and at least the charge light circuit might be able suggest a possible fix. Someone could make some decent money if they made up detailed swap wiring diagrams. Whole harnesses aren't needed, just diagrams clearly showing the connections.
 
#8 ·
Joseph,I wish the wiring diagrams were as simple as that.I have had several combinations in the garage for the swap,almost all had at least a wire or two different.
What we run into--82,83,84,85 all have minor differences in there wiring,at least one or more wires have to be pinned different. 84/85 is actualy just the fuel pump pin as I recall,83 has a different plug for the engine to body harness



87-88 seem to be identical.When you get to an 89 harness,the plugs change and at least one wire.In 90 we get another different plug,that goe to the body harness,needs at least 2,I believe 3 wires re-pinned.I'm am just starting on a 84/92 sub-harness,I'll know more about this wiring in about 2 weeks.

All this babble may be confusing.It's tough for me to get it all straight,and type all the thoughts that come out,in an order that makes sense.
 
#9 ·
hey joesph its Rob the guy with the red 84 supra that has the same problem as you i have feul and turn over but i don't have that ing problem call me on my cell we'll have to get together i have a couple ideas like i think my computer might be a problem or the 89 wiring on my 90 something engine

you should check your ignitor box, your risitors all your coils your cam postioning senor, and any of your connection to the fallowing, but i have the same problem and I'm going nuts

Maybe I should come see your project i might help the both of use

call me (905) 380 8484

your friend

Rob Maier
 
#12 ·
I remember a post quite a while back on the yahoo list concerning the voltmeter light problem. It should have nothing to do with the spark problem, tho. There was something you had to do on the earlier mk2's to resolve the light problem. May want to do a search on the yahoo list.

I'd be interested to know how you resolved it, if you have. Please update.

Christian
 
#13 ·
Unfortunately I haven't solved my wiring issues. According to the resistance specs in the TSRM my coil packs are bad, so I got new ones but I'm afraid to plug them in since I don't know why the first ones went bad (the engine started and ran fine in the mk3). Other than that almost no progress. I just don't know where to start, I thought all my original connections were correct. I'm considering trying to find another mk3 harness and just putting the whole thing in the car. Other than that I don't know what to do. I can't afford a $1000 Reg harness (if he still makes them) so I'm kinda screwed. I've even considered trying to find a nice mk3 with a blown engine to put my rebuilt 7M in. Then at least I could put the 5M back in and the car would be driveable. I haven't driven a Supra in so long :( I'm so depressed, I'm gonna have to drive my 300ZX to the Toronto meet. Alright well now I'm really upset so........
 
#14 ·
Dont feel so bad. I'vebeen mk2-less for over 2 yrs since I blew up my 5mgte. Been dilly dallying on the 7m build. Now I'm hauling ass to get this done by mid sept. I'm going on vacation then and when I get back i go to the Vegas meet. Right now I've got everything from A pillar foward stripped to the frame. I'll be painting it next week (if my FG hood ever gets here), and hopefully in about 2 weeks I'll be doing the wiring. I have an 82 also, so maybe we can compare notes and find out whats the deal with yours. I'll let you know when I get to it.

Christian
 
#15 ·
I'd see if you've got 12V at the ignitor. No juice to the ignitor equals no spark. Then try and trigger the coils manually with a couple of AAs. If you have power to the ignitor and you do this you should fire the corresponding plugs. If this is true your problems lie with the ECU not triggering the ignitor. So you probably have issues upstream from the ECU (i.e. CPS). I'd doubt coils are the problem, especially because you'd have 3 to go bad at once. I'm not sure about the 7M coils, but I replaced my original coil because the resistance was off and the new coil from Toyota was the same. I don't know if it was a typo or what.
 
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