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Old 03-06-2014, 07:02 PM   #1
ccorbin81
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Default Tricky Ignition

Hello,

I have had this thing sitting in my garage for some time now 88 Supra Turbo Hard Top, I can finally afford the body work I need but I am still struggling with ignition issues.

My car turns over fine but does not recieve fuel. If I jump 12v+ into the B+ Diagnostic port, it cranks and runs fine aside from some old gas making it sputter.

Here is what I know, I have multimeters and everything electrical on hand but I can't get to the bottom of the problem. I also have all of the wiring diagrams but I admit I am barely a neophyte when it comes to automotive circuit diagrams.The Diagnostic port has no power (actually I think one of the ports had a small amount of voltage), trying to jump B+ to FP does nothing, however jumping 12v+ to the B+ port enables everything. My check engine light does not come on when I turn the ignition switch on, when I jump power to the B+ the CEL comes on with ignition on and turns off after the vehicle starts. I cannot, for whatever reason, check for codes with or without jumping power to the B+. I have rewired the CPS wiring with a high temp weatherpack connector, no change, still runs with power jumped to the B+.

The ignition switch has correct voltage, I don't remember the wires but they were listed in a post by CRE and they checked out like he said they would. I have changed the switch and cylinder anyway but there has been no change. All of the fuses and links in the ignition circuit seem to be ok but I wouldn't be suprised if I missed a fuse or relay. I have changed all of the cylindrical relays I can find under the hood and in the driver kick. I have replaced and tested all fuses that I can find.

The car worked great, I slid into a pole going about 15mph and I just need a bumper and pass headlight replacement. The car had to sit outside for a couple of months during heavy rain before I got it inside but it stopped starting after it sat in the garage for several days.

Im capable with a meter but Im getting lost on the diagram, does any of this information help any of you more veteran wire monkeys? If there is a good post on a thorough ignition troubleshoot I would love to have a link.

Thanks in advance,
CC

Last edited by ccorbin81; 03-06-2014 at 07:22 PM.
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Old 03-07-2014, 07:28 AM   #2
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I don't really have time atm to go over the wiring diagram as I'm off to bed, but I *think* a bad circuit opening relay can kill power to most electronics in the car. IIRC, it's located in the driver's kick panel. Check for voltage there with key on and proper operation of tbe relay.
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Old 03-07-2014, 07:37 AM   #3
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So I went ahead and checked the wiring diagram, and the circuit opening relay directly controls power to the B+ terminal in the diagnostic box, the fuel pump relay, the ecu, and just about every critical efi sensor on the car. So I'd definitely start looking around there
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Old 03-07-2014, 03:17 PM   #4
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Good morning,


I pulled out the relay this morning located in the driver kick. Here are the specs I found for testing it.
  • STA - E1 = 17 - 25 ohms
  • +B - Fc = 88 - 132 ohms
  • +B - Fp = Infinite ohms (i.e. open circuit) w/ relay off
  • +B - Fp = 0 ohms w/ relay on
I tested it with my meter and here are the results.
  • STA - E1 = 21ohms
  • +B - Fc = 121ohms
  • +B - Fp = OL
How can I safely energize the relay to test (+B - Fp = 0 ohms w/ relay on)? Or is this irrelevent? It seems the relay is functioning properly, is there anything between this relay and the diagnostic port B+?

Should the terminal where B+ for this relay connects get 12v with ignition on? I don't get any voltage on any of the pins when I test them with ign on and off.

Last edited by ccorbin81; 03-07-2014 at 03:24 PM.
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Old 03-08-2014, 07:41 AM   #5
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I'm not sure how to test it on the vehicle, what I've always done in the past to test 12V relays is make a "harness" (a couple wires and some female spade connectors) to plug into the coil side of the relay. I then just hook the other end of the harness into the car battery and check the continuity of the switch side of the relay.


I'll admit I'm also not the best at deciphering wire diagrams, but it seems to me that the B+ power starts at the 15 AMP EFI fuse in the underhood fuse box, then through the EFI Main Relay (which I believe is also in that fuse box). The more I'm reading, the more I'm starting to think that I may have jumped the gun on suggesting the circuit opening relay, as it seems the contacts are only closed while starting and while air is moving through the AFM.
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1989 7MGTE R154 Targa Top White Package w/Blue Interior
Driftmotion 57trim CT26, Upgraded Intercooler, 2.25" Hard Pipes, 3" Turbo Back Exhaust with Test Pipe, HKS VPC w/GM 3 bar MAP sensor, APEXi S-AFC, Walbro 255lph fuel pump, ProSport EVO Series Boost / Fuel Pressure / AFR gauges, Lotek a Pillar Gauge Pod, HKS Type 0 Turbo Timer, Eibach Lowering Springs, Tokico Illumina II TEMS struts, custom powder coated Motegi Racing TrakLite wheels
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