car will not crank
 

Hey guys and gals,

I am frustrated and I hope y'all can help. I just did a S5 TII swap using the stock S5 n/a harnesses. The problem is the starter will click but it will not crank. It is a brand new starter and I can get it to crank when I jump the terminals. The battery has been charged and reads approx. 12v with the key on.

I think the problem is a wiring issue between the engine/front body harness. I tried messing around with 5 wires but nothing seemed to work (other then the oil pressure gauge jumping off the end).

5 wires:

-Big red/black stripe wire (with black connector). 0v with the ignition on or off.
-smaller black/red stripe wire (connects to the oil pan sensor). 0v with the ignition on or off.
-Yellow with red stripe. 0v with the ignition on and ~9 with the ignition on
-Yellow with Black stripe. 0v with the ignition on and ~9 with the ignition on
-Black ground on the bell housing

I tried to search the diagrams on here but the colors did not match up: Foxed.ca - Mazda RX-7 Manuals

Any help with be greatly appreciated.

Thanks!

jumper the spade connector on the starter to the battery cable stud on the starter, if it cranks then there is a fault in your ignition starter wiring circuit. you can run a meter down to that black/white wire and see if its registering 12v with the key turned to crank, if it is then the circuit is intact but likely lacking the amperage to kick the starter solenoid over any longer, if that's the case i have starter booster relays that bypass all the BS of the crank circuit.

I jumped the space in the middle with the side of the starter and it cranked. One side of the starter reads a constant 12v while the other side is dead with the key on or off. I got a brand new battery but same results. I did noticed that when I hit the key, the radio shuts off then flickers back on. Am I missing a ground somewhere? I got the one ground on the battery, base of the shock tower, top starter bolt, and the one on bell housing.

There are three wires to the starter, one is from the positive terminal of the battery which of course will have constant voltage, the second wire is a ground which of course will have no voltage and the third wire (thinnest gauge) is for the starter solenoid which triggers the starter to activate (it will not have voltage unless the key is placed to the start position). Your problem is this wire. And there are fuses used to start the car and fuses not used to start the car. The fuses not used do not receive voltage when starting the car and the radio fuse is one of them thus that is why the radio stops when starting the car.


Find the starter cut relay which has one plug w/4 wires next to the main relay. The Black/Blue wire should have voltage w/key to start, does it or not? If it does then check to see if the thicker of the two Black/Green wires at this relay also has voltage w/key to start, does it? If it does then your problem might reside at the interlock switch which requires the clutch to be depressed to start the car and if it fails then the voltage on the B/G wire coming from the relay will not make its way through the interlock and on to the starter solenoid. If it did pass through the interlock then the Black/Red wire coming from the interlock to the starter solenoid would have voltage and the starter would turn over.

Thank you for the detailed explaination! I traced it back using the steps above and it ended up being a disconnected red/black wire that was tucked next to the big connector on the frame rail. Up next... trying to get it to actually start. Thanks again.