What happened to the old ECU? Once it was out could you see an obvious problem.
CEL/DTC "Check Engine" Light, but no codes??? (2 Viewers)
- Thread starter bamachem
- Start date
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- Thread starter
- #42
They didn't even open it up. It has been thrown in the junk pile as far as I know... I didn't care to keep it because I marked the old one w/ a permanent marker and verified that it had been changed. Once I saw my mark, I knew it had been swapped and they were going to stand behind their diagnosis of it being a faulty ECU.
JunkCrzr89
Competent Ignoramoose
Reviving this thread because I’ve encountered a similar problem as @bamachem did back in 2011.
Three days ago, CEL came on with codes P1300, P1315, and P1330, which are malfunctions in the IGF/IGT circuits at coils 1, 4, and 7, respectively. All three cylinders are on the same IGF1 circuit with cylinder 6, which is not throwing a code. It also had code P0300 for random misfire on multiple cylinders. Truck runs fine and doesn’t feel like it’s misfiring, and mpg has not noticeably declined.
I first pulled the coils and plugs for those three cylinders and inspected them. I replaced all coils and plugs with new Toyota units 50k miles ago, so unsurprisingly they all looked OK. But I swapped in three new Denso plugs anyways that I keep as spares (just in case), cleared codes, and DTCs immediately came back on the same cylinders.
So I then implemented the stepwise process in the FSM for troubleshooting these codes. Results are as follows:
1. Ground check - Resistance between the ground at each coil connector and body ground checked out fine.
2. Power check - Ignition ON, voltage between pin 1 (+) and pin 4 (-) on each coil connector was 12v, which is in the acceptable range.
3. Open circuit checks - ECU connector unplugged/Coil connectors unplugged: Resistance between the IGF1 pin at ECU connector and the IGF1 pin on each connector, as well as resistance between IGT1, IGT4, and IGT7 pins at ECU connector and the corresponding pins at each coil connector all checked out fine.
4. Short circuit checks - ECU connector unplugged/Coil connectors unplugged: Resistance between IGT/IGF pins at each connector (both ECU and coil connectors) and body ground were all OL, so checks out fine.
5. Voltage checks - ECU connector plugged in, coil connectors unplugged, ignition ON: Voltage between IGT1, 4, and 7 pins at each coil connector and body ground were all 4-5v, so within acceptable range.
I think I’ve ruled out the coils or wiring being the source of the issue. What am I missing here? A voltage check between each IGT pin on the ECU connector for each cylinder and body ground? Or a voltage check between the IGF1 circuit pin on the ECU connector and body ground? At what point do I try a different engine ECU, or will this even work if the ECU is not flashed and reprogrammed to my keys?
Three days ago, CEL came on with codes P1300, P1315, and P1330, which are malfunctions in the IGF/IGT circuits at coils 1, 4, and 7, respectively. All three cylinders are on the same IGF1 circuit with cylinder 6, which is not throwing a code. It also had code P0300 for random misfire on multiple cylinders. Truck runs fine and doesn’t feel like it’s misfiring, and mpg has not noticeably declined.
I first pulled the coils and plugs for those three cylinders and inspected them. I replaced all coils and plugs with new Toyota units 50k miles ago, so unsurprisingly they all looked OK. But I swapped in three new Denso plugs anyways that I keep as spares (just in case), cleared codes, and DTCs immediately came back on the same cylinders.
So I then implemented the stepwise process in the FSM for troubleshooting these codes. Results are as follows:
1. Ground check - Resistance between the ground at each coil connector and body ground checked out fine.
2. Power check - Ignition ON, voltage between pin 1 (+) and pin 4 (-) on each coil connector was 12v, which is in the acceptable range.
3. Open circuit checks - ECU connector unplugged/Coil connectors unplugged: Resistance between the IGF1 pin at ECU connector and the IGF1 pin on each connector, as well as resistance between IGT1, IGT4, and IGT7 pins at ECU connector and the corresponding pins at each coil connector all checked out fine.
4. Short circuit checks - ECU connector unplugged/Coil connectors unplugged: Resistance between IGT/IGF pins at each connector (both ECU and coil connectors) and body ground were all OL, so checks out fine.
5. Voltage checks - ECU connector plugged in, coil connectors unplugged, ignition ON: Voltage between IGT1, 4, and 7 pins at each coil connector and body ground were all 4-5v, so within acceptable range.
I think I’ve ruled out the coils or wiring being the source of the issue. What am I missing here? A voltage check between each IGT pin on the ECU connector for each cylinder and body ground? Or a voltage check between the IGF1 circuit pin on the ECU connector and body ground? At what point do I try a different engine ECU, or will this even work if the ECU is not flashed and reprogrammed to my keys?
