Engine control mick module. If the engine control relaly's output is not there, the ECM is not powered up, it is as simple as that.
The ECM fires the plugs and fuel injectors. WIthout them operating, the engine cant run.

Additionally, the ECM enables the starter (and disables the starter when the engine gets to 400 RPM), without the ECM powered up, the starter is not going to engage.

 

 

They do not, fractures in the paths to the engine control relay, as well as pitted relay contact and open relay coils are what cause the no crank.
There is more to the RCM issue than just fractured solder on the pins to the air pump, that is only one problem - the least serious problem.

 

 

I'd have to look at it. There is a connector going to the air pump and a connector going to the harness that leads to the ECM.
ONE of them is the "air pump failure" and one is the "mystery no start". I always go thru every single solder land, even the relay holes, diodes holes, every one. I re-flow the solder on every joint on the board, It takes all of 90 seconds.

 

Right, fitted brand new battery, still no crank. Checked all battery cable connections. Removed RCM and checked all PCB tracks, components, continuity checked all pins to board, and tested all relays with good quality Fluke DVM. Re-fitted RCM with cover and switched ignition on, fuel pump relay operates and then releases after a few seconds (correct) and ECM relay operates and stays operated (correct). I'm confident RCM is good.
Now, pulse module, I see from starter wiring diagram, the circuit from key goes through the PM before reaching starter solenoid, anyone know what the PM does ? How to check ?
Am going to jack car up and check starter and solenoid.
Mick

 

Right,
Have proved starter motor OK by applying 12v to the violet/white from Pulse Module to solenoid, engines cranks over fine.
Have confirmed 12v from ignition switch start position to Pulse Module, but no 12v out to starter from Pulse Module .
Now, is Pulse Module faulty or is there an inhibit from somewhere stopping start 12v going to starter ?

 

I switched ignition to On/Run, I then removed the wire from the Pulse Module that goes to the solenoid and applied 12v to crank engine.
Engine cranked OK but engine did not start ?

 

The ECM has to tell the pulse module to engage the starter, then, as the engine starts, once 400 rpm is achieved, the EMC tells the pulse module to drop the starter.

So what appears to be the case is this:

• The ECM is not telling the pulse module to engage the starter.
• The ECM is not firing the plugs and fuel injectors (probably for the same reason as bullet #1 above)
• The problem is, you have got to figure out why the ECM is not happy.
  • If you turn the key to "ON" (Not accessory, but ON), wait 30 seconds. Does the engine fan warp up to high speed? If so, that tells us the ECM is not powering up fully. We can work on that.
  • If you turn the key to "ON" (Not accessory, but ON), wait 30 seconds. If the engine fan DOES NOT warp up to high speed - the ECM is appears to be coming alive - but there is something it does not like. We can work on that.
  • Which of these situations we are dealing with involve different paths of diagnosis. Find out which one you are faced with.

 

Oh, and STICK WITH THIS ONE THREAD, or none of us can keep up with what is going on.
Creating multiple threads does not help. It drives the help away.

 

Ignition switched to ON/RUN for >30 secs, fan does not run. Have tested connections to Pulse Module and confirm permanent 12v to 1A, RUN switched 12v to 2B and START 12v to 1B, and Ground on 5A. Am measuring 3.4v on the Pink/Red wire to the PCM and 0v into the Pulse Module 2A terminal.
I am assuming the Sensor Ground connection at 2A is expecting a ground from the PCM to enable start ?
I can get a 2nd hand Pulse Module from eBay for $15, I'm tempted to buy as I could then eliminate faulty PM ?
Your advice is very much appreciated.
Mick

 

With the key in the ON position, there should be 2 relays that remain engage (fuel relay engages then drops).
Is this what you see?

 

With key in On/Run position, the Engine Control relay operates and the Fuel Pump relay operates. After 2 to 3 seconds, the Fuel Pump relay releases, leaving only the EC relay operated.

 

tighed1, are you saying 3 relays should operate and one (Fuel Pump) releases after 2/3 seconds leaving 2 relays operated ?

 

Pizzaguy,
I posted this to the 'pulse module not sending signal' thread:

Pizzaguy,
Have you seen my replies to the thread RCM as you requested ?
Also, the only connection between the PM and ECM(PCM)is the Pink/Red wire from terminal 2A. It is marked 'sensor ground' which seems to be the mis-labelled connection ?
Mick

 

Right, just intercepted the pink/red that goes from PM pin 2A to ECM, with ignition switch to On/Run and Start positions, I measure +12v.
I agree that the pin labelling must be wrong as the 'sensor ground' label in the manual doesn't make sense ?
I'm going to buy the used PM off eBay and see !
The 12v I measure could be the enable signal to the PM ?
A Very Frustrated Mick

 

The book says that line is not "high" or "low" but is pulsed to enable and pulsed to disable the starter. I am still not convinced this is accurate. Swapping the pulse module is not a bad idea, we did that at a tech day (since we had 6 or 8 cars) - in our case, the pulse module was not the issue, turned out to be a clutch interlock switch.

But DJ asked you about the relays - do not skip over what he said - if you have one less relay activating, that has to be resolved!

 

I replied to DJ earlier but no reply yet. I thought his advice was a little confusing, not clear if he meant 2 or 3 relays should operate ?
When I switch ignition key to On/Run, 2 relays operate (ECM and Fuel Pump), then Fuel pump releases after2/3 seconds. This is correct as ECM releases Fuel Pump relay if it doesn't detect the motor turning via the CPS. The only other relays are the Air Pump, Horn and Traction control

 

The traction control relay also pulls in when the key is "ON". If it does not, you get all sorts of issues - remember, the TCS is what operates the wheel speed sensors and feeds that data to the ECM and instrument panel.