2000 Prius doesn't start

Hello,

I've bought a 2000 prius (gen 1) that doesn't start as a fun project (hoping that it was the HV battery). After checking each cell, the HV battery seems fine(at least 7.2V per after a charge-discharge cycle). Then, I've noticed that the car main problem is with the fuel injection system. When I try to start it, MG1 spins the engine for about 3-4 seconds then it stops. It gives a P3191 and P3101. So, checked the sparks - those are OK. Checked the camshaft and crankshaft sensor with the oscilloscope, the signal seems as expected. Checked the E7(10)-E8(16) circuit, the signal seems OK - I think that this is the signal for the EFI. Measured the internal resistance for the camshaft sensor: 2kohm, crankshaft sensor: 1.2kohm. Checked the throttle body - clean. The problem is that I have no signal on the injectors. I have a +12 V (black and white wire), but when I crank the engine, no command comes on the injectors. Checked at the output of the ECM - same "missing" signal.

Ok, i thought that I need to change the ECM. Bought an ECM from ebay, same part number and version (89661-47041). Installed the "new" ECM, same problem. Tried the "pin" in the OBD port (short between pin 4 and 13) to "pair" the ECM with the imobilizer. Left the car with key on for a little over 30 minutes. Still no luck.

First question: For the 2000 prius, you need to pair ECM like for Gen2?

After a few more tests, I've noticed that when I put the key in, and the dashboard lights come on, the "cold" and "hot" coolant light come on. Also, sometimes after cranking the engine, the radiator fan comes on. Now, today are about 10 degrees Celssius. I think this should not happen. On the OBD, I get 6C engine coolant and 10C air temperature. This seems about right.

Second question: Is possible for a broken coolant sensor to cause no command on the injectors?

As a last test, I tried cranking the car and using a starter spray in the air intake - the car works while I spray. Run it for a few minutes - it works with no problems.

Forgot to mention that I've also checked the EFI relay and fuses.

For me, I am left with the following possible problems:
1. Coolant sensor
2. A second bad ECM or a first-one bad, and second one not paired with the mobilizer. But I get no immobilizer error and the immobilizer light comes off when using the key.

Any idea would help.

Thanks,

 

OK, I figured out. It turns out that the fuel tank was full ... with diesel. The previous owner told me that it died about 20 km after filling the tank. Disconnected the injector ramp, switched the fuel pump on, removed about 45 liters of diesel mixed with petrol, added another 5 liters of petrol to the tank, removed it, then filled the tank with 100 petrol, removed diesel from the fuel ramp, started the car, after a few "misfire" errors it works perfectly. I can say that diesel in the fuel tank will give a P3101, P3191 and after the HV battery is empty (a few starting attempts), it will give a P3000 and some random errors starting from ABS to immobilizer. Drove it today about 50km, it works perfectly. For the first 5-10 km serious white smoke (I think from the diesel in the evacuation maybe ?), but now it works normally.

 

I've called the old owner, he told me that he didn't refuel himself, but asked a employee from the gas station to fill it. When I bought the car, I've noticed that the owner drove a diesel SUV (Mercedes). The Prius was used by his wife, but he took it for a trip. I think he got confused and may told the employee "fill it up with diesel".

Anyway, what is to remember, that this will generate only P3101 and P3191 and no other error code, until the HV battery is empty (when you get lots of random errors). Also, MG1 will crank the engine, and it will seem that the car starts for a few seconds. Actually is just MG spinning the engine, with no ignition whatsoever.

Also, he got to the Toyota service and the diagnosed the "random" codes caused by the HV battery being empty. They told him he needs a new battery installed. When I opened the HV battery to check it, I've noticed that it has been rebuilt using Gen2 or 3 modules (the ones with metallic walls - gen1 is only plastic). Diesel in Prius is a extremely rare situation, so I've checked for this only after 2 weeks of checking computers, harnesses, sensors, injectors, relays and so on. Priuschat was extremely helpful with resources and links. Also, I've noticed that if you mix diesel with petrol, it will smell like petrol.