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Matt
Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 21622
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Suzuki Swift 2006. Just moved if off the drive and now won't

Resolved Question:

Suzuki Swift 2006. Just moved if off the drive and now won't start again. Battery good, engine cranks over fast. I suspect ECU problem or fuel pump not energised - is there a fuel safety cut off perhaps? I tried to connect OBD scan tool but it won't connect to ECU, previously this tool worked before when I checked to see if any DTCs.
Submitted: 1 year ago.
Category: Car
Expert:  Matt replied 1 year ago.

Hello

as you're not able to get communication with the ECU then I'd start by checking the ECU fuses for damage / cracks etc and then use a meter to see if there's 12V at the fuse with the ignition on

you don't say what model / engine size this is but there should also be an ECU power relay in the fusebox under the bonnet

if there's power at the fuse check to see that this relay is clicking under your touch when the ignition is flipped on

Customer: replied 1 year ago.
It is a 1.5 GLX. Yes there is 12 volts on the IG coil and FI fuses. I checked the relays also - was able to swap over fuel pump with another (since they are all the same part number). It seems the ECM is not triggering - the OBD scan is not able to establish a connection to it. I also ruled out immobiliser since the keyless unlocks and the ignition turns, and no key symbol appears on the dash.
Expert:  Matt replied 1 year ago.

hello

if there's 12V on the fuses then you're right in saying its not the immobilser

but it sounds likely that the ECU isn't opening the fuel injectors, if the injectors are working you can hear them click - its difficult to hear them with background noise so use a long screwdriver like a stethoscope, placing the handle end in your ear and the metal tip against the body of the injector whilst your assistant turns the engine over.

If you can't hear anything check the ECU power is present by measuring voltage at the fusebox and on its relay socket if OK then check the connections to the crank speed sensor and consider replacing this sensor if the wiring / connections look OK

If the car will start using a squirt of quick/ easi start into the intake then this confirms the problem is lack of fuel

Customer: replied 1 year ago.
Still won't start. ECU power is present. Main power relay is energised by signal from the ECU/ECM.
But my main concern is that no OBD scanner tool is able to connect to the ECU - I have tried several professional mechanic and cheap bluetooth LYL ELM327 modules.
Expert:  Matt replied 1 year ago.

Hello

OK if there's ECU power then the next step is to check the state of the small earth wires that run out of the engine bay wiring and are secured to the engine with small bolts and ring terminals

these wires are the ECU earth connections

if this is OK then I'd say the next step is to get the unit sent off for testing

http://www.autoecu.com/

http://www.ecudoctors.com/

http://stores.digitalautotech.com/StoreFront.bok

Expert:  Matt replied 1 year ago.

Hi

do you still need help?

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Customer: replied 1 year ago.
I traced the circuit back and it seems the main relay power supply whilst present on the fuel relay and the coil pack, injectors is supposed to be a welded splice that together also feeds the ECM power pins. I checked the ECM harness and pins 1 and 16 seem to be open circuit. There is not supposed to be a break or a switching module in between - however there must be a junction connection somewhere as the wires are distributed via two separate wiring looms. For now I fixed it using an auxiliary relay to power the ECM pins triggered by the ignition on switch.Anyway thanks for your help.

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