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85 Supra starting question

6K views 27 replies 12 participants last post by  SteveGranger 
#1 ·
Howdy! I have an 85 Supra, automatic transmission. I've had the car about 6 months, it has just under 70,000 miles on it. On very random occasions it won't start.

The scenario: put the key in, turn it to first position and everything lights up as usual, turn further to start the car and nothing. No clicking noise, No whirring noise, absolutely nothing at all.

I should note that the shifter wobbles and is loose so my thinking has been maybe there is a contact point that has to be completed when the car is in park for the car to turn over and the few times this has happened I move the shifter into Neutral and then back to Park, usually have to do this a few times and it's worked. It just happened yesterday and I must have played with the shifter for a good ten minutes.

Just wondering if anyone else has experienced this problem and any feedback on what this could be.

thanks,
Jamie
 
#4 ·
Can you reproduce it by shaking the shifter around when the car is otherwise starting fine?

The switch operating the neutral-start inhibitor can wear with time, so it's a safe bet. Intermittent faults are hard to diagnose though. If you're having trouble, put a continuity meter on the connectors in the engine bay (so it beeps) then wiggle the shifter around. If the beep is momentarily interrupted, replace the switch.
 
#7 ·
I once bought an 84 mk2 at the Texas Can Academy charity auction that had been donated because it wouldn't start and they couldn't figure out why. Sometimes it would click but mostly nothing, radio, fan, etc worked, just no crank. After doing the standard diagnosis, it was obvious that the PO or their mechanic had cleaned the battery terminals, and was visibly OK but what they failed to do was to thoroughly check the battery cables. I cut the insulation on the positive battery cable and found that under the insulation was badly corroded about 2 to 3 inches. If the only thing making any connection is the few outer stands of wire, then its not enough. Its got to be able to send electrons all the way down the core of the wire too. After replacing the positive battery cable (and the negative just for good measure), the car started every time, ran and drove just fine. Always diagnose and replace in order of cheapest first to most expensive last.
 
#9 ·
Get an ohmmeter and check the resistance from B+ terminal to starter or use a voltmeter to measure voltage from starter input bolt to chassis or Bat +. S.b. less than 0.1 Ohm or more than 6 volts when starter is initiated.
 
#11 ·
thanks for the replies. was taking the negative battery cable off and noticed a smaller wire next to it just loose. turns out it was connected to the main negative cable but had corroded through and was barely providing any ground. stripped it and reattached and so far no further problems.
 
#19 · (Edited)
I posted about battery cable corrosion based on your symptoms, but you never posted that you checked as I described. Since one of the secondary grounds was corroded all the way through that makes me suspect the battery cables even more. Seriously, they can look like brand new, having been cleaned on the outside, but there still may be enough corrosion inside the insulation to prevent enough amps from getting through to the starter. Everything else will work that runs on just a few amps, but the starter won't budge without a couple hundred and won't even click without 30. Take a razor blade and cut a slit in the battery cable insulation from the terminal back about three inches. If its green under there, replace the cable. If not, get some red or black heat shrink from Frys, suture it back up and start other diagnostics. But the rule is always check the least expensive parts first as if you don't really know, then you could wind up paying a shop $300 to replace a starter when all you needed was a $20 battery cable or a 50 cent fuse.

Automagic? It also sounds like it could also be the neutral safety/reverse light/gear selector position switch. When you put it in reverse, do your backup lights come on? If no, then its out of adjustment or broken.
 
#12 ·
well, back to square one. Problem started happening again, a lot. Generally I'll drive the car somewhere close by, never more than a mile away (gas station, grocery store, etc) turn off the car for a few minutes to maybe 15 minutes. Come back out and the car won't start. Doesn't happen every time but has happened about 5 times in the last couple ten days. took the car to a shop, explained everything, after about a day at the shop they called and said they can't find any issues with the electrical and suggested replacing the starter. considering the age of the car I agreed.

this was two days ago and this morning drove the car from my house to the 7-11 about a quarter mile away and it happened again.

it does eventually start again, usually takes a few minutes. the car is an Automatic so I'll move it in/out of park a few times. I also popped the hood to look at the battery wires, make sure everything was connected.

getting frustrated and don't think the mechanics I go to for the regular stuff are solid for this electrical work.

any recommendations for a really good diagnostic tech in the Dallas area for these older Toyotas? I'm in Carrollton, TX to be specific which is on the north side of Dallas. Any help would be appreciated. thanks
 
#13 ·
Get a dvm with an ohmmeter.Blindly check continuity for all the wires in the starter circuit per the tsrm.A good connection has less than 0.1 Ohm resistance. Also jiggle the wires near the wire ends that you are checking By the car "won't start" you mean that nothing happens when you turn key or starter solenoid clicks? Need more details.
 
#14 ·
when this situation happens, I put the key in, lights come on as normal but nothing happens when it should be turning over. no clicks, no whirring noises, nothing at all. I usually at this point turn off the radio, fan and a/c just in case there is something I should be hearing but so far nothing. this has probably happened about a dozen times in the past few months but at least 5 times in the past couple weeks.

I have to be honest here and say that I don't know much about electrical testing. I have looked at connections at the battery, taken cables on both sides off, cleaned them, made sure all is making good contact but it doesn't seem like it's mattered. main reason I'm trying to get a recommend on a good tech in the dallas area.

thanks for your reply
 
#15 ·
OK,you have a "Turn the ignition key and NOTHING"happens symptom.
Let the local auto repair shop have it overnight,because they need to replicate the situation/symptom.
In the meanwhile(I suspect hot soak issues),let the car cool down,if it's warm.
Try hood open for a while.
Bad starter cable/starter possible.
Thanks for cleaning the connections at the battery.
Inspect the negative cable where it attaches to ground.Wiggle it.
 
#16 ·
hi triple D, thanks for the reply. It was at an auto shop for about 36 hours earlier this week. they couldn't get it to happen no matter what they tried...figures right :) they said they checked numerous connections between the battery/starter/ignition and grounds and nothing to report they thought perhaps it was a bad starter and suggested replacing it. Considering the diagnostic charges would've only been a little less than the starter replacement cost I went ahead and let them replace the starter.

worked fine for about a day and then happened to me again this morning.

I did go back and recheck the battery connections and all the ground connections I could find. unbolted the battery cables, cleaned everything, etc and reattached. Now I just wait and see but I'm hoping someone in the Dallas area will have a good recommend for a shop that specializes in older imports and electronics.

thanks again
 
#21 ·
As Phil said, check the battery cables a few inches from the battery. Any signs of green, replace immediately.
If it's the neutral start switch which allows starting in either neutral or park, wiggling the shifter in either position should help. It would be unlikely to be flaky in both positions at the same time. However, the adjustment of this switch is critical. Like Phil said, do your back up lights work when in reverse? If not or if they're intermittent too, more than likely that switch is out of adjustment. It's very expensive to replace as it has contacts in every position to inform the ECT ECU what position the shifter is in. Check the TSRM for proper adjustment.
However, it's probably the cables. Might be time to get a cheap DVM and learn how to use it.
 
#24 ·
As mentioned earlier, the positive and negative battery cables needs to be tested electronically:

1. Measure resistance from end-to-end, should be zero.

2. Measure voltage-drop of battery when cranking. Then measure voltage-drop at starter, should be same

3. Measure continuity of NSS in neutral and park. Wiggle the shifter. Should never lose continuity. Do 2nd test and bypass NSS with jumper wire to simulate neutral/park position.

4. activate starter by manually triggering solenoid. Don't need to say that car should be in neutral?


You simply cannot test the battery cables by looking at it and saying it "looks good". Need to test them electronically and cut back the insulation and inspect the actual wires inside. Might be like this underneath:


 
#25 ·
Excellent picture Danny. That's exactly what I found on that 84 that had been donated to charity because it wouldn't start - lots of green copper under the insulation.
 
#26 ·
so an update on this problem. I was referred to a shop in the Dallas area owned by a 15 year Toyota master mechanic. dropped the car off and they ended up pulling the Neutral Start Switch. turns out all the contact points inside were fairly corroded and gunked up and barely making contact. They cleaned everything and reinstalled and not a single problem since.

I also had a wobbly shifter due to pieces being worn out and/or cracked.

All told I paid $500 and this is based on their $55 hourly rate. A little more than I would've liked but honestly to now have a reliable car it was worth it.
 
#27 ·
so an update on this problem. I was referred to a shop in the Dallas area owned by a 15 year Toyota master mechanic. dropped the car off and they ended up pulling the Neutral Start Switch. turns out all the contact points inside were fairly corroded and gunked up and barely making contact. They cleaned everything and reinstalled and not a single problem since.

I also had a wobbly shifter due to pieces being worn out and/or cracked.

All told I paid $500 and this is based on their $55 hourly rate. A little more than I would've liked but honestly to now have a reliable car it was worth it.
 
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