Need help finding short

[mk3_supra]

Let me start by telling you about the car. I've got an 1987 supra 7mgte auto, after about a year or so of chipping away at the various problems I've had with the car I've finally got it close to running condition. I tried to start her up it cranked and fired up. It was having trouble maintaining idle and the head lights would dim. I feared either the battery or the alternator was bad. Thought about just pulling the alternator for a reman'd one and replacing the battery but I wanted to check if they were bad first. So I took the volt meter with the car off battery charge was sitting at 12.25v, with the car running it read 14.6v so all seemed well except I had to hold the accelerator to maintain idle to get a reading.
Then I wanted to check if I had a short, so I disconnected the negative terminal hooked up the test light and sure enough it lit up. I pulled every fuse one by one but the light stayed on. No check engine light on. I'll see if I can pull any codes tomorrow just got off work and a little tired and sore especially having to snake my way around the steering wheel to get to the fuses. What else or where else should I look? Also any suggestions on the idle problem?

 

[Scruggs86.5T]

How are you hooking up the test light? If you are just hooking it from the positive terminal to the neg. wire then the light should be on. All the light is telling you is that there is a difference in potential from the neg. lead to the positive terminal which in my mind would make the test light, light up. Which would mean that you dont have a short. Try pulling the positive terminal off of the battery and running a resistance check on the pos. and neg. leads of the battery. This would tell you a lot more. Hope this helps some. Also Mike has an EWD posted for the 87' here;
http://www.supracentral.com/ewd/

 

[mk3_supra]

I'm pulling the neg terminal and connecting the test light to the negative lead to the neg terminal with the car off. I will give it a try though thanks for the link.

 

[Scruggs86.5T]

Ok that makes since. Yeah, you definately have a short then. Hope the link helps some.

 

[89supra7mgte]

Its a draw not a short i believe. Would think a short to power or short to ground would blow fuse or burn wires. When you are checking with the light hooked up in series between neg terminal and neg wire make sure all your accessories are off. When you were in car did you have the door open? will make test light light up. what you need to do is either pull the courtesy fuse or get a screw driver and shut the door latch as if it were closed. Also from my experience sometimes a test light is not that consistent, a meter works good too and you know what you amp draw is. Try using both.

By the way what you after, battery dying or the idle problem? def pull codes.

 

[jetjock]

^ Finally, someone gets it right...

 

[mk3_supra]

Yeah talked to some guys at work about my problem...was quickly corrected. I'm potentially looking for a parrasitic draw.
Yes the door was open while I was pulling fuses a bit hard to get them without it but hopefully I can get it in running enough shape to drive down to my shop and to pull out the ammeter we've got here. Will update if anything comes up.

 

[89supra7mgte]

easy way to correct the door issue is to just close the latch. test light works good but sometimes depending on the bulb it will light when you have an ecu with keep alive memory (newer cars) but is within spec on the amp draw. I think if you are under 300mv you are good (.003 v) someone correct if i am wrong. How bright was the light?

 

[hvyman]

How bright is the light is never a good question as you'll never know if its exactly that bright again.

 

[89supra7mgte]

Yea i meant it as in some test lights will be bright as hell with low amp draw and some that dim with a big amp draw. think that is all in the bulb though? I dont prefer the test light method much rather know what the amp draw is with a meter.

 

[hvyman]

Amp, ohms, and volts all play a roll in how bright the light will be. The only time i use a test light is when im looking for a popped fuse or a power wire which i end up getting a volt meter to check its voltage to make sure anyways.

 

[89supra7mgte]

very true. They both work good just depends on how your using it. think for a draw best would be the meter imo. For shorted wires i actually bought this power probe kit, has attachments that will plug into fuse sockets light bulbs and such, works damn good.