Need major help

[keisler]

New to this web site, hopefully not breaking any rules here for re-posting. I need serious help with my SC400; Can an after market Alternator (NEW) cause a SC400 not to start? I have a post going already with 16 hits and only 1 reply, so I thought I would give additional info. I have checked all grounds and cables. I have replaced Alternator (NEW after-market, about 9 weeks ago), battery and starter. I have checked the anti theft system. I have reset the computer. I have learned alot from looking at previous post but still can't seem to get this problem solved. I now have carpitunnel (spelling?) in my right hand. My SC has been in the shop on the rack for 5 weeks now and my tech is pulling his hair out. The battery has a full charge and just turns over. Something in the ignition system is causing this SC not to fire. All of your collective help is needed on this problem so I don't have to 2nd mortgage my house to pay for this. Thank you in advance.

 

[JBrady]

Always check fuel and spark first. Confirm fuel pressure and injector pulse. Confirm spark.

 

[chrisman]

hi,, the ignition sysytem in the sc is like many other toyota cars.. in other words,, it is not any more complicated/expensive then any other except for the fact that its a v8.. the sc400 has 2 distributors, 2 coils and 2 ignitors.. these relly on 1 crank sensor, and 2 cam sensors.. i think,but may be wrong, the ignition may only need the cranks sensor, and the cam sensors are used for the injection.. the ecu decides when to fire, and sends a signal to each of the ignitors,, the ignitors then control the voltge/signal to the coils which then send a spark to the distributors..

so,, first thing i would do is see if the coils are "sparking",, re3move the coil wire going to the distr, and place it near a ground.. check for spark.. if you dont get a spark,, -especially from either coil,,check the ignitors and the crank sensor..
if you do get a spark,, check rotors-distributors..
i dont remember off hand,, but i will get the info on how to check the ignitors and cranks sensor..until then,, start going over basics,, and lets hear what you come up with..

 

[keisler]

Confirmed that I have no spark. Could this be caused by an after market alternator not sending a signal through the ecu and ignition system?

 

[keisler]

I passed all this to my mechanic, he is checking the basics. thanks. Please keep searching for me so we can get this fixed.

 

[chrisman]

hi kiesler, the alternator--even if it was not working,, should not affect the ign sysytem..BUT,, if some wires were shorted while removing the alternator you may have a problem.. check to make sure power is going thru the entire power circuit/ system..that you havnt shorted out a major fuse somewhere while removing the alt..
usually--these things turn out to be something simple, but overlooked..

 

[keisler]

I have checked that wiring from the alternator and all grounds. All fuses check good. Have never had a car that just turns over and over and want crank up (fire).

 

[Zuffen]

I had a phone call from a member stuck on the side of the road with the same problem.

After a bit of discussion we decided to check power going into the ECU.

Turned out it had blown a fuse supplying power from the ignition switch to the ECU. He replaced the fuse and drove it home.

I would go back to basics and check the ECU has power where it should. You will need to check the wiring diagrams as it should have a few 12v feeds to the ECU.

 

[keisler]

A fuse would be an all time thing. My problem is intermittent. Have you seen the ECU go out on this model and if so as it was going bad be intermittent?

 

[Zuffen]

Have you thought about a corrroded contact anywhere between the battery and the ECU ( the power doesn't travel all that far) or the earth side of things.