C280 W202 Coil voltage
08-14-2017, 02:04 AM
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1995 C280
C280 W202 Coil voltage
Mercedes Benz C280 1995 W202
Can anyone tell me what the voltage on any of the coil plugs/connectors should be with the ignition switched on?
What plug: To be more specific the round plug/connector from the engine wiring harness that connect to any of the 3 ignition coils.
I have a starting issue and am only getting between 9.3 - 9.5V. Not sure if this should be closer to 12V.
Can anyone tell me what the voltage on any of the coil plugs/connectors should be with the ignition switched on?
What plug: To be more specific the round plug/connector from the engine wiring harness that connect to any of the 3 ignition coils.
I have a starting issue and am only getting between 9.3 - 9.5V. Not sure if this should be closer to 12V.
08-14-2017, 05:34 PM
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Thx Russell.
I have the model with the bio-degradable harness and had to redo it. Even when i unplug ECM connector 2 and test the voltage on the ignition coil pins(9,10,21) straight from the ECM I get the same voltage reading. So the wiring harness is not the issue.
Also tested the voltage on all 3 pins feeding the ECM power on connector 1 and all have 12v.
Looks to me like the ignition coil circuits on the ecm is fried or i have a fueling issue causing the engine to die after 2-3 seconds even if the spark is weak.
Enyone had this issue before?
I have the model with the bio-degradable harness and had to redo it. Even when i unplug ECM connector 2 and test the voltage on the ignition coil pins(9,10,21) straight from the ECM I get the same voltage reading. So the wiring harness is not the issue.
Also tested the voltage on all 3 pins feeding the ECM power on connector 1 and all have 12v.
Looks to me like the ignition coil circuits on the ecm is fried or i have a fueling issue causing the engine to die after 2-3 seconds even if the spark is weak.
Enyone had this issue before?
08-15-2017, 02:54 PM
#4
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The ECM has nothing to do with supplying the power!
Have a look at the connector block on the passenger side near the washer bottle. It has a black plastic lid that flips open. Under it you will find 2 10mm nuts (battery supply ) and also a small 7mm nut (ign supply) to coils and injectors. Make sure that nut is tight and also check the voltage there!
Have a look at the connector block on the passenger side near the washer bottle. It has a black plastic lid that flips open. Under it you will find 2 10mm nuts (battery supply ) and also a small 7mm nut (ign supply) to coils and injectors. Make sure that nut is tight and also check the voltage there!
08-16-2017, 07:26 AM
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Tested the 2 right-hand side 10mm connectors of the 3-pole block(X12/3). It has 12v and seem to run straight from the battery. The 7mm connector also has 12v but only when the ignition is on.
Tested the ignition coil connectors again and realised the voltage between the center pin and ground(engine block) also has 12v. But between the center pin and second round pin has 9.3-5v as mentioned before. Between the 2nd round pin and ground(engine block) i get 1.9v.
Therefore the confusing reading before was caused by assumed the second pin was ground but seem to be rather a low voltage signal wire. The problem lies somewhere else. It still dies after running for 1-2 sec the first time i try to start it every day, but fails to start on every subsequent attempt. Unplugging the MAF sensor makes no difference. Not sure what to test next, i dont have a code scanner.
Tested the ignition coil connectors again and realised the voltage between the center pin and ground(engine block) also has 12v. But between the center pin and second round pin has 9.3-5v as mentioned before. Between the 2nd round pin and ground(engine block) i get 1.9v.
Therefore the confusing reading before was caused by assumed the second pin was ground but seem to be rather a low voltage signal wire. The problem lies somewhere else. It still dies after running for 1-2 sec the first time i try to start it every day, but fails to start on every subsequent attempt. Unplugging the MAF sensor makes no difference. Not sure what to test next, i dont have a code scanner.
08-17-2017, 04:42 PM
#6
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The coil has only 2 wires forget about HT wires now. The 12v is pink red I think and the ground which is a pulsed from the ecu is black or black white.
Start and dies can be throttle body or most likely a lack of fuel. Also if your car has red green lamps on the interior mirror make sure they not flashing with the ign on. Meaning immo active
Start and dies can be throttle body or most likely a lack of fuel. Also if your car has red green lamps on the interior mirror make sure they not flashing with the ign on. Meaning immo active
08-26-2017, 06:49 AM
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Tested all 6 HT spark leads using a spark tester, getting spark on all.
Tested all 6 fuel injectors and getting a signal using a noid light on all.
Both were tested while cranking.
Then removed the fuel filter and switched the ignition on, showed no fuel is being pumped. Discovered there was no fuel in the tank even though the fuel gauge is showing a quarter tank. Added fuel but still not being pumped to fuel filter. Discovered the fuel pump was not getting power. After some testing figured out the green relay in the boot was blown. Jumped connectors 30 and 87 which fixed the power to the fuel pump for testing purposes.
Still no start.
Disconnected the inlet fuel line connector right before the fuel rail and confirmed fuel is pumped to this point. Also checked the return line next to the rail, confirmed it was returning the fuel.
Next I'll test the fuel pressure on the rail but dont understand why its not starting.
Tested all 6 fuel injectors and getting a signal using a noid light on all.
Both were tested while cranking.
Then removed the fuel filter and switched the ignition on, showed no fuel is being pumped. Discovered there was no fuel in the tank even though the fuel gauge is showing a quarter tank. Added fuel but still not being pumped to fuel filter. Discovered the fuel pump was not getting power. After some testing figured out the green relay in the boot was blown. Jumped connectors 30 and 87 which fixed the power to the fuel pump for testing purposes.
Still no start.
Disconnected the inlet fuel line connector right before the fuel rail and confirmed fuel is pumped to this point. Also checked the return line next to the rail, confirmed it was returning the fuel.
Next I'll test the fuel pressure on the rail but dont understand why its not starting.
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08-26-2017, 01:43 PM
#8
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Are you saying when u crank the engine is there spark at the plug. Also you can listen if injectors tick. If u have fuel delivery. Pressure will be fine
08-26-2017, 05:56 PM
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Tested for spark by pulling the HT lead of the installed spark plugs, then inserting a spark tester with its own spark plug and grounding the plug on of the head cover bolts. Then crank the engine and check for the tester to light-up and for its spark plug to spark.
This was done one spark plug HT lead at a time.
Couldn't hear the fuel injectors tick as i was standing next to the driver door to work the ignition switch for each test. The bosch noid light do light up on each injector. Tested them one by one cranking the motor each time.
This was done one spark plug HT lead at a time.
Couldn't hear the fuel injectors tick as i was standing next to the driver door to work the ignition switch for each test. The bosch noid light do light up on each injector. Tested them one by one cranking the motor each time.
