My car doesnt start. I hear the start relay working but no turn over on the engine.

I started to troubleshoot. Had an extra ignition switch that I tried to swap out but still same issues. Also tried to jump start with 2 different vehicles and wouldnt work.

So I checked the terminals at the ignition switch:

terminal 30 1/2 = 12v
terminal 50 when cranking is 6v with the start relay in and 12v with the start relay removed.

So I checked terminal 30 at the start relay and its 12v with the relay out and 6v with the relay in.

So it seems that there is voltage drop from the relay's terminal 87 which goes directly to the starter. Would like to confirm whether its the cable from the start relay to the starter or the starter itself. Anyone know what type of tests I should do?

 

I think you should spend a little more time looking at the battery. It's easy to screw up the jump process and not get a good connection. Your measurements do point to a bad battery. I would suggest you bite the bullet and switch out the sucker with a known good battery.

 

It is like a 6 month Bosch battery and I just started the car earlier in the morning before it died.

I will take it to Pep Boys to get tested just in case. I guess I should also check voltage drop with everything connected while cranking at various points.

battery -> ignition switch
ignition switch -> relay
relay -> starter solenoid

Should eliminate the cables being the problem.

 

Is your car manual? If so check the clutch switch to make sure it is engaging.

 

Yup checked the clutch switch and its is working fine. I am running an aftermarket ECU also but I swapped in my stock ECU to make sure it had nothing to do with that.

 

I was thinking about the engine ground. On the right side just beside the right turbo....

 

Checked it and looks tight and clean.

Checked the battery also and it is good. Could handle 850 CCAs.

Going to pull the starter and bench test I guess. Anyone know a good trick for removing the top bolt? Getting frustrated with twisting my arm trying to get it off. Will try an impact gun next.

 

Well not the starter, bench tested with both solenoid and just directly to the starter itself.

Back to looking at that engine ground now. Will it help if I ground the motor at a different spot and see if I can start the car? (should have done this earlier). I can just hook up a jumper cable from the starter itself to the chassis somewhere.

Anyone have DIY on how to replace that ground? Is it doable in garage without dropping motor?

 

Ignition switch most likely. Very common fault.

 

Already swapped it.
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I changed the starter already but waiting on parts for a new ground strap. Original one requires 3-4 weeks from Germany so gonna Fab my own.

I think it's the starter but doesn't hurt to replace ground strap. Starter can spin on my bench but maybe not when load on it.

I hand cranked the motor too so it ain't seized.

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I went through 3 switches before I got one that worked consistently. Just sayin'

 

When you mention relay do you mean the starter relay? Or the start lock relay? BTW you can test the starter while it is still in the car by shorting between terminal 50 and terminal 30 with a screwdriver if it cranks starter is ok.
The attached diagram shows that the circuit contains a start lock relay controlled by the engine ECU and anti-theft controller and located on relay support 2 opposite to the ECU support - I had problem similar to yours when a mouse got into the car and chewed through the red and blue wire connected to terminal 7 of this relay

 

Just replaced starter and ground wire and car starts now. Probably was the starter that fixed it.

I mean the start lock relay. I did short terminal 50/30 with a screw driver and it didnt do anything. But I assumed it was because I didnt hold it long enough (sparks scare me).

Thanks all that helped troubleshoot.