2007 Mazda 3, 2.3L 5MT, no crank after timing / head repair

Hello all,

I found this thread in my search for information on my issue and it was quite helpful, but I'm still stumped...

www.scannerdanner.com/forum/post-your-re....html?start=17#59132

The car sat for about 10 months because we didn't need it at the time. I went to move it from where it had sat all that time and with a boost, the engine started for about 1 second and then abruptly quit and would not start again. However the starter motor cranked just fine. There was no compression in any cylinder so through some reading I decided that the VVT sprocket had cratered. I have replaced it along with the timing chains and guides etc. I had also read that some people had experienced valve damage in this situation so I decided to remove the head and make sure everything was good and it was. I had a machine shop pull the valves, give it a good clean and reassemble with new valve stem seals and everything went together nicely. However, now it won't crank.

The only modification to the vehicle is an aftermarket remote starter.

I have installed a new battery as the old one was toast anyway.

I took a jumper wire from B+ to the signal wire on the starter solenoid and the solenoid works and the starter cranks just fine.

I have verified that all the fuses and relays are good.

I do have 5V at the IAT sensor with the key on so I'm confident that the PCM is communicating.

I removed the signal wire connector on the starter solenoid and replaced with a shiny new spade connector to ensure that corrosion is not causing a bad connection between the fuse box and the solenoid.

I have confirmed continuity of the signal wire from the solenoid back to the fuse box pin where the relay plugs in. (the Grey wire in the diagram below)

I have swapped the starter and heater relays and the heater works with the starter relay so I am confident that the relay is good.



Using this diagram with my circuit tester connected to B -ve I can verify that I have 12V constant power at the battery side of the load circuit of the starter relay. I believe that there should be 12V power from the ignition switch to the control side of the relay with the key on and there is not, but the tester does light when I put the ignition in the start position. This is where I'm confused.

I feel like there should be 12V on the switch side of the relay when the key is on and then when I turn the key to the start position, the PCM should provide ground to complete the control circuit, closing the load circuit and sending power to the starter solenoid. What am I missing here?

Please help.
Charlie

Monde wrote:

The key should be in the START position to get power at the control side of the relay. Are you missing control?

This is my question. Should there be 12V at the control circuit in the ON position or only in the START position?

The thing that's really tweaking my melon is the fact that I verified that there is continuity between the relay pin and the solenoid, and yet, when I jump the load side of the starter relay (where I have 12V constant power) the starter does not engage, even though if I run a jumper from B+ to the solenoid it does engage.

I'm baffled.

Wytbishop wrote:

This is my question. Should there be 12V at the control circuit in the ON position or only in the START position?.

Wiring diagram is drawn as hot in start only. To confirm you have control unplug the starter relay and put a test light across the two control terminals in the relay base. Then turn the key to crank with the clutch depressed. If the light illuminates you're good on the control side.

Wytbishop wrote:

The thing that's really tweaking my melon is the fact that I verified that there is continuity between the relay pin and the solenoid, and yet, when I jump the load side of the starter relay (where I have 12V constant power) the starter does not engage, even though if I run a jumper from B+ to the solenoid it does engage.

Continuity and open circuit voltage tests will tweak your melon :silly:

Jump the load side then check for voltage on the jumper. If voltage is good ypur problem is towards the starter. If it ain't there's a issue with the feed.

Well it turned out to be the corrosion in the wire from the fuse box to the starter solenoid. Matt nailed it. The wire had continuity, but wasn't transmitting enough current to activate the solenoid.

Now it cranks but won't fire. At least I can tell it has good compression again. I'm sure something is just disconnected somewhere.

Thanks for your help.