1997 Tacoma 2.4, No Spark, No Start, Can't Solve. Impossible Fix?

I think you are gonna need ignition wiring diagram. Make sure that match with your car.

This is what i've found in a quick search

Also at this point we don't know if injectors are firing neither.

If injector are not firing, neither spark plugs we should focus on if crankshaft signal is getting PCM.

The crankshaft sensor ohms are within range. However, I cant tell if theyre communicating (ecu and crank sensor).

I know the injectors arent firing. I smell no raw fuel in my tail pipe after cranking.

How many wires does your crankshaft sensor have?

It has 3.

Then try this:

Unplug CKP and check in conector terminals

1. Ground pin: This terminal has continuity with block engine (close to 0 ohms).

2. Power pin: This terminal has voltage once you turn ignition switch on.

3. Signal pin: The one which is not ground, neither power.

Once you identify signal, plug ckp again and check voltage in signal line while cranking. You should see not a constant voltage, but at least a change compare to "no cranking"

I found the signal wire, and the ECU is sending me a signal at 5.8v. When I crank it, it drops lower.

But something bad happened. A loud electrical 'snap' sound happened under the hood while I was testing those terminals at the CKP. Now I don't have any power at all.

**edit, now I have power after waiting 5 minutes**. That was weird.

I had another look at the resistance on my CKP, and its now 1378! Cold reading on the FSM is: 1,630 - 2,740

Could that low reading mean failure of an out of the box new sensor?

I would say resistance is not an accurate test. It's better test voltage drops (with available tools).

Remember we are trying figure it out just with a voltmeter. That's why we are doing this. If you get a scope that would be faster.

5.8 volts could be a good average, depending of other factors. Let's complete ckp test with the following:

With ignition switch on (no crank) rotate crankshaft by hand (very slowly). You should be able to see voltage jumping from 0 volts to power source voltage.

It better if you perform this test in ecu connector. That way we can discard sensor and wire at the same time.

To make the engine start the ecm needs valid ckp and cmp signals. The cmp signal, an AC-sine wave is generated by a coil inside the distributor and enters the ecm at pin 5 and 18 in the E8 connector.

The ckp signal, an AC-sine wave as well, is sent to the ecm at connector E8 as well, entering at pin 4 and 17.

With these inputs the ecm sends a signal to the igniter to activate the ignition coil. This is the IGT signal and enters the igniter at pin2; it's a square wave. The igniter then grounds the primary of the ignition coi through pin 5 at its own connector, accordingly to the IGT signal. Taking away this ground will induce the spark in the secondary.

Once ignition successfully has taken place the igniter sends a confirmation to the ecm. This is the IGF signal and enters the ecm in E8, pin 3.


These are the signals you have to confirm in this pretty straight forward ignition system.....


The ecm won't send further IGT signals if it does not receive the IGF signals, so make sure this circuit is not grounded or open.

Check the mentioned signals/circuits and report your findings.

Thanks for that explanation, this should help along with guafa's turning that crank over by hand and recording the results at the ECU. Ill do this tomorrow.

Juergen, unfortunately, I dont have an ocilliscope to read those signals. This might be something I'm unable to do (determine what signals are what).

Nice!!. Very opportune information juergen.scholl. Thanks.

Forget about CKP test mentioned by me before (sensor is different)

That means CKP wires are:
1. Noise shield: The terminal which has continuity with engine block.

2. Coil: The two wires which are not ground

You can check AC voltage while cranking between the two coil terminals (same thing in CMP coil terminals mentioned by juergen.

It is supossed that in "no cranking" and ignition switch on, you should no see any voltage

Edit: moving crankshaft by hand, you can't see any voltage, because you need certain speed you can't get by hand

If the battery voltage is down to 11.8 volts I would give it hours on a charger on a low amps setting before doing more testing

Hi Everyone,

I cant detect any signal at the E8 plug at the ECU / wire 5 or 18 as Juergen suggested. But then again, I'm not using an oscilloscope. No voltage seen, just zeros.

You should be able to see an AC-voltage with your multimeter..... If you don't see nothing check for a signal directly at the sensor. If you have a signal there then check the wire for continuity/integrety to the pcm.

With a sound battery you should get at least 500mV from the ckp while cranking, I'll attach a screen shot from a good sensor, same year, same engine. Engine is running, so the voltage is higher.

DO YOU HAVE THE CORRECT WIRING DIAGRAM?

Brianzero, just to be clear.

1. You have to measure AC voltage
2. Measure voltage between pins 4 & 17 (ckp) or 5 & 18 (cmp)

You mentioned "5 or 18" (i suppose you mean one test lead to ground and the other to 5 or 18, which is incorrect)

Juergen, i had 5.8v at the ckp while in the ON ignition position, and while cranking the starter, i had 5v. A bit of voltage drop. This was testing the plug that connects to the ckp (ckp unplugged during test.)

guafa wrote: Brianzero, just to be clear.

1. You have to measure AC voltage
2. Measure voltage between pins 4 & 17 (ckp) or 5 & 18 (cmp)

You mentioned "5 or 18" (i suppose you mean one test lead to ground and the other to 5 or 18, which is incorrect)

UPDATE:

Ignition in ON position.

I have voltage at pin 4 and 17 (E8 plug on the ECU) It appears to be 0.54v at both pins. These are the CKP pins at the ECU.

That voltage in CKP is good. Is telling you pcm is comunicating with CKP sensor (we don't know if synchronized with mechanical TDC).

So, you don't have spark, neither injection pulse. Seems PCM is detecting something else (or not seeing other signals).

This probably wont help, but I will check that the distributor is aligned properly while the engine is at TDC. I was thinking that might be another 'something' to check off the list, according to the FSM, the distributor pickup acts as a CKP of sorts, and if the pickup isnt aligned, the symptom is the same as having a failed CKP (or non communicating CKP).