ECM .... Smoked 2 of them in a row
- Thread starter jk kelly
- Start date
Where does the harness go to from the ECM to where?
X2
no
- Joined
- May 26, 2001
That is good advise, find the short.
I smoked 2 ECM's on a customer's car before I found the wiring to the trans had a short in it?
Fortunately for the owner and me, Turbo Bob was able to repair them.
Have you done any mods or upgrades or any work around the engine or under the dash recently? If so, start looking there for a bare or crimped wire.
i found the transistor it smoked and its the same one on both ecms.. how do i find what it goes to? its on the bottom board kinda in the middle, there is another one close to it and some numbers on the board around it with 103
RmvBfrFlght
Well-Known Member
- Joined
- Sep 28, 2007
Here are some threads that discuss how the ECM and fuel pump relay operate. The first thread has a picture of the transistor that drives the relay.
http://www.turbobuick.com/forums/posts/3193510/
http://www.turbobuick.com/forums/threads/intermittant-fuel-pump.382182
That transistor supplies +12 volts to the relay to activate it. Either the relay coil is shorted or the wiring has a short to ground.
RemoveBeforeFlight
http://www.turbobuick.com/forums/posts/3193510/
http://www.turbobuick.com/forums/threads/intermittant-fuel-pump.382182
That transistor supplies +12 volts to the relay to activate it. Either the relay coil is shorted or the wiring has a short to ground.
RemoveBeforeFlight
turbodave231
Moderator
- Joined
- May 24, 2001
You most likely have a relay, solenoid or injector that is drawing too much current. Here is the way we test these and identify the culprit:
1. Disconnect and remove the ECM
2. Using the wiring diagrams identify every pin on the ECM harness that controls an injector, solenoid or relay
3. Configure a DVOM to measure current. Ground the negative lead of the meter.
4. With the key in the run position, one at a time, ground each of the pins you identified in step 2. This will cause the relay, solenoid or injector to turn on. (you are acting like the ECM)
5. Write down the results. Look for the circuit that pulls too much current. Also OBSERVE that the item being controlled TURNED ON! A circuit that doesn't work is probably the culprit.
*The one exception to this procedure is the Fuel pump relay. The ECM uses a High Side Driver to turn on the fuel pump relay. It sends out 12v to turn on the relay instead of providing a ground. To test this circuit/relay, move your grounded meter lead to 12V+
From memory here are the relays and solenoids:
AC relay
Cooling Fans
Boost control solenoid
Evap canister solenoid
ERVR (EGR) solenoid
all six injectors
*Fuel pump relay
I've used this procedure to fix cars that blow multiple ECMs.....it works.
1. Disconnect and remove the ECM
2. Using the wiring diagrams identify every pin on the ECM harness that controls an injector, solenoid or relay
3. Configure a DVOM to measure current. Ground the negative lead of the meter.
4. With the key in the run position, one at a time, ground each of the pins you identified in step 2. This will cause the relay, solenoid or injector to turn on. (you are acting like the ECM)
5. Write down the results. Look for the circuit that pulls too much current. Also OBSERVE that the item being controlled TURNED ON! A circuit that doesn't work is probably the culprit.
*The one exception to this procedure is the Fuel pump relay. The ECM uses a High Side Driver to turn on the fuel pump relay. It sends out 12v to turn on the relay instead of providing a ground. To test this circuit/relay, move your grounded meter lead to 12V+
From memory here are the relays and solenoids:
AC relay
Cooling Fans
Boost control solenoid
Evap canister solenoid
ERVR (EGR) solenoid
all six injectors
*Fuel pump relay
I've used this procedure to fix cars that blow multiple ECMs.....it works.
- Joined
- Feb 18, 2006
To fry that quick it must be a dead short.
Check the plug for the oil sender.
Check the plug for the oil sender.
turbodave231
Moderator
- Joined
- May 24, 2001
Looking at the original post, It wasn't clear how quick the ECM was damaged.
Remember, the ECM supplies ground to turn most things on (fuel pump is the exception). So if there is a short in a controlled circuit, it has to be a short to power to hurt the ECM.
I've repaired vehicles where a solenoid winding went bad (low resistance) which causes the ECM to sink too much current to ground. This doesn't happen too often, but it will make you pull your hair out trying to find the problem. Just thought I'd share what I've learned.
Remember, the ECM supplies ground to turn most things on (fuel pump is the exception). So if there is a short in a controlled circuit, it has to be a short to power to hurt the ECM.
I've repaired vehicles where a solenoid winding went bad (low resistance) which causes the ECM to sink too much current to ground. This doesn't happen too often, but it will make you pull your hair out trying to find the problem. Just thought I'd share what I've learned.
Replaced fuel pump transistor in ECM , have power to fp relay harness when key is turned on for 2 seconds still won't crank unless I jump b and d terminals out then it cranks, that is the only way to get the fuel pump to run,also bought a relay from autozone.
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