HELP!!! No Spark. Pulling Hair Out!! Please...

[kgriff]

Hi everyone. I've finally reached 15 posts. Whew! That was harder than I expected.

Please forgive the long post, but I've got a lot of information.

Anyway, on to my story...
96 4Runner, 3.4L, 5 speed, 220k.
My wife names vehicles. Her name is "Birdy"
The 72 Jeep that you'll read a bit about later is "FrankenJeep"

Bought Birdy about 2 years ago with about 170k. Super clean, all highway miles. Previous owner must have had a Golden Retriever because I'm still finding dog hair here and there.

So, a while back, I walk out in the morning, start her up. Fires up immediately, just like always. Runs for a couple seconds, diesels for a moment, then dies. Nothing I can do just then, so I switch the child seat to my 72 Jeep pickup, take my son to daycare, and I'm off to work.

My first thought is that the timing belt either broke or at least lost some teeth. That's how it behaved as it was dying. So, back home later, pull the timing cover. Timing belt still intact(YAY), with no missing teeth(YAY). Reach down with a socket and breaker bar and turn the engine over to line up timing marks. Everything lines up correctly.
Not the timing belt.

Now it's time to start troubleshooting; fuel, spark, air...
Do I have fuel pressure - Yes, 50ish psi
Do I have spark - No. Aha!!
So, I start in with the troubleshooting stuff from the factory service manual(Thanks to the post in this forum, by the way) and whatever else I can think of.
Fuses - All Good.
MAF - Good
Cam Sensor - Good
Crank Sensor - Good, but the mounting ear broke when I was taking it off, so now she has a new Crank Sensor.
TPS - Good
Igniter - Good

I should mention at this point that I have access to a 97 T100 that has a lot of the same parts. I was able to swap both the TPS and the Igniter. In both cases, the T100 ran with 4Runner parts, and the 4Runner didn't run with T100 parts.

Wiring from ECM to Igniter - Ohm'd all out and all wires good.
Wiring from Igniter to Coils - same
Power to Coils - Check
Voltage from IGT1-3 and ground at ECM - All good. (pg. EG-295 in FSM)
Voltage from IGF and ground at ECM - Good (pg. EG-294)
Resistance of plug wires - Good
Resistance of coils, primary and secondary - Good

Oh, I installed new spark plugs at some point in this project. They were due anyway.

Engine Coolant Temp Sensor - The one near the front of the engine that feeds the ECM - Good

Ignition switch - swapped with known good one - didn't fix problem.

So, now I'm grasping at the proverbial straw. Trying to come up with anything that might cause my no spark condition. Find a used ECM, install that. No go.

Open up my Haynes manual. There's a bit in there about using an LED test light to check that the coils are getting a "fire" signal. Finally found an LED test light. No "fire" signal. (No surprise there, right)

I've checked every point above multiple times, hoping to see something different. Of course, nothing has changed.

The only other thing I can think of is that this 4Runner has the "Toyota V.I.P. Security System" I've never used this system, previous owner had never used it. The only thing I know for sure is that if I unplug the brain box under the driver's seat, the engine won't crank at all. I downloaded the owners manual today, but it's no help. Is there any way that this security system could create a no spark condition?

So there we are, and here I am. Between my wife and I, we have this 4Runner, her Jeep Liberty, and my 72 Jeep J2000 pickup. Wouldn't you know, two days ago her Liberty took a big giant dump in the driveway also. (Burned valves, I think. Goodie. Just what I need. A valve job right now.) So, we're down to the 72 Jeep. No Bueno. She works the next town over. I'm self employed and can travel anywhere up to 300 miles from home. No vehicle, no good.

Can anyone please help? That is assuming you made it all the way through my very long story.
In the FSM, page EG-292, there is a block diagram under "Igniter Circuit Malfunction". It shows the inputs and outputs for the ECM. On the inputs it shows, "Camshaft Position Sensor, Crankshaft Position Sensor, and Various Sensors". Can anyone tell me what comprises "Various Sensors"?

Is there a fuseable link somewhere that I don't know about?

Is there some other silly sensor that would cause a no spark condition?

Ideas? Thoughts? Suggestions? Make fun of my plight? All would be welcome.

Oh, I've also talked to mechanics at three different shops. All of them say pretty much the same thing, "You could bring it in if you want, but it would be a waste of time and money. I'd just do the same things you've already done." Drat.

Yes, I'm that desperate. I'm 47 years old and have never taken a car to a shop, but I'm at the point where I'm so far out of ideas that I'd happily turn this over to someone for diagnosis.

:ybrick::ybrick::ybrick::ybrick::ybrick::ybrick::ybrick::ybrick::ybrick::ybrick::ybrick::ybrick::ybrick::ybrick::ybrick::ybrick::ybrick::ybrick:

 

[Plastics guy]

Have you gone through your fuses and the relays with an ohm meter to verify they are working properly. Sounds like you have done everything that I can think of myself.

 

[phattyduck]

Any CEL codes?

-Charlie

 

[kgriff]

I've checked all fuses and all relevant relays. All check good.

I did have one code prior to her shutting down. P0120. Throttle Position Sensor. However, as stated, the TPS is good and works correctly in a T100, whereas the T100 TPS didn't cure the 4Runner problem.

Edit - The P0120 was set several days prior.

 

[CB3G_GM]

Will it crank with the security brain plugged in?

Based on your troubleshooting so far I would do a comprehensive check of all the wiring associated with the security brain (assuming you can't get the vehicle to crank). I'm pretty sure in the event it thinks you're stealing the vehicle it disables the starter.


EDIT: If it DOES crank the next thing I would do is swap your cam sensor from the T100. I've worked on a few CPS that ohmed okay but didn't provide a signal that satisfied the ECM.

 

[St Runner]

Tough one to figure out. You have done a pretty thorough job checking everything. I also think you should test the security system. And whenever you get into these weird electrical issues always double check your grounds. Especially the one on the back of the block to the firewall and the one from the battery to the fender. Poor grounds can cause sensor failure

 

[kgriff]

It will crank with the security system plugged in. Won't crank with the security brain unplugged. My problem with this security system is that I don't really know what it actually does. Does it just stop the engine from cranking, or is there some mode in which it will let the engine crank but shut down spark?

I will try swapping the cam sensor with the T100. At this point, anything is worth a try, and it sounds like the sensor can check "good", but still not satisfy the ECM. Have you seen this condition with other sensors? I haven't swapped the MAF with the T100. Might that be worth a try?

I've checked all grounds. The only other thing I could do with grounds is disconnect, clean, reconnect. Ohming everything out, all grounds are good.

 

[kgriff]

Question...
Does anyone know if I can swap the 4Runner ECM into the T100?
I don't want to put the T100 ECM in the 4Runner just yet. (Both are manual tranny and the connectors are the same.) I don't have connector pinouts for both, so I can't say positively that they are the same.

 

[CB3G_GM]

It will crank with the security system plugged in. Won't crank with the security brain unplugged. My problem with this security system is that I don't really know what it actually does. Does it just stop the engine from cranking, or is there some mode in which it will let the engine crank but shut down spark?

I will try swapping the cam sensor with the T100. At this point, anything is worth a try, and it sounds like the sensor can check "good", but still not satisfy the ECM. Have you seen this condition with other sensors? I haven't swapped the MAF with the T100. Might that be worth a try?

I've checked all grounds. The only other thing I could do with grounds is disconnect, clean, reconnect. Ohming everything out, all grounds are good.

I guess I assumed you had already messed with the MAF but yeah... so... I would swap MAFs THEN try swapping cam sensors

 

[kgriff]

All I've done with the MAF sensor is check it static, and with flow. Both tests say it's good. Still...won't hurt to swap with the T100, assuming they are the same. Unfortunately, I won't have the T100 again until Sunday.

 

[gamefreakgc]

Question...
Does anyone know if I can swap the 4Runner ECM into the T100?
I don't want to put the T100 ECM in the 4Runner just yet. (Both are manual tranny and the connectors are the same.) I don't have connector pinouts for both, so I can't say positively that they are the same.

No, they are different. Same with Taco's.

Clean/swap the MAF. It's one of the few sensors that will prevent the engine from igniting. You found the big ones, crankshaft sensor, camshaft sensor but the MAF is the other odd one that will keep the engine from working.

 

[kgriff]

No, they are different. Same with Taco's.

Any idea what the differences are? I know the part numbers are different. From what I've found out, the 96 ECM doesn't interchange with any other year. It was a one year deal, then changed. Anybody know why or what changed?

 

[4Reak Show]

I would make sure to check for ground/power AT THE ECM connectors. Most likely it has more than a few wires that need constant ground/power. Since a wire could be broken inside the harness it could check good on the engine block but not be making its way through to the computer.
For example, there's a little ground wire on the driver side of the upper intake by the "diagnostics" box and if that comes loose it would give you your symptom. (Ask me how I know that)

Also, have you checked injector pulse? That includes putting a light in line with an injector and see if it flashes. If you don't have injector pulse AND spark your talking about an ECM that's refusing to turn on or isn't getting an input.

My money is on a missing ground or power feed to the ECM. Either broken wire or pad ignition switch or something. Just a wild guess

 

[gamefreakgc]

Any idea what the differences are? I know the part numbers are different. From what I've found out, the 96 ECM doesn't interchange with any other year. It was a one year deal, then changed. Anybody know why or what changed?

Toyota likes to switch around wires and wire colors without telling anyone. I just went through creating a custom wiring harness for my ECU, and every year except for 98 was different. All it takes is one wire to be different (older/new MAF, wideband vs narrowband O2 sensor, etc. etc.) and it won't work right.

I'm not even sure the connectors will fit right into the ECU. The shapes of the plugs changed too.

 

[kgriff]

I would make sure to check for ground/power AT THE ECM connectors. Most likely it has more than a few wires that need constant ground/power. Since a wire could be broken inside the harness it could check good on the engine block but not be making its way through to the computer.
For example, there's a little ground wire on the driver side of the upper intake by the "diagnostics" box and if that comes loose it would give you your symptom. (Ask me how I know that)

Also, have you checked injector pulse? That includes putting a light in line with an injector and see if it flashes. If you don't have injector pulse AND spark your talking about an ECM that's refusing to turn on or isn't getting an input.

My money is on a missing ground or power feed to the ECM. Either broken wire or pad ignition switch or something. Just a wild guess

Thanks for the tip. Now all I gotta do is find the correct pin out for the specific ECM I've got. Should be possible.

Time to get more intent on checking proper grounding of EVERYTHING.

Yes, I have checked injector pulse. All is good on every injector. The only thing I haven't done along those lines is to check and make sure fuel is getting injected. I figured spark first, then fuel if she still won't start after I've figured out the spark issue.

 

[kgriff]

Toyota likes to switch around wires and wire colors without telling anyone. I just went through creating a custom wiring harness for my ECU, and every year except for 98 was different. All it takes is one wire to be different (older/new MAF, wideband vs narrowband O2 sensor, etc. etc.) and it won't work right.

I'm not even sure the connectors will fit right into the ECU. The shapes of the plugs changed too.

Thank you for the info. In this case, I do know that the connectors are the same. I've looked at the T100 ECM, some time back, only to discover it was a different part number.

Oh well, it was worth thinking about. At least the T100 has a lot of the same sensors and components that can be swapped if need be.

 

[LittleCaesar]

So you know the igniter is OK but there is no signal to all three coils correct?

Do you have access to a scanner to read live data? I would be curious to know if it reads correctly but as 4reak Show said, look for bad grounds. Check the main ECM fuse as well.

 

[schmauster]

Good luck on this, im working on a similar problem

 

[kgriff]

So you know the igniter is OK but there is no signal to all three coils correct?

Do you have access to a scanner to read live data? I would be curious to know if it reads correctly but as 4reak Show said, look for bad grounds. Check the main ECM fuse as well.

Correct. No signal to all three coils, igniter known to be good.

Live data follows, for the 4Runner and T100. Both not running, key on(obviously). The T100 is warmer as it was driven a couple hours ago.

ODBII Item 4Runner T100
Fuel System 1 Open Loop Open Loop
Fuel System 2 Not Supported Not Supported
Coolant Temp 78°F 143°F
Load Value 0.0% 0.0%
Short Term Fuel Trim 0.0% 0.0%
Long Term Fuel Trim 0.0% 3.9%
Engine RPM 0 RPM 0 RPM
Vehicle Speed 0 MPH 0 MPH
Ignition Timing Adv 5° 5°
Intake Air Temp 102°F 125°F
Air Flow Rate 0.00 lb/min 0.00 lb/min
Throttle Posn(No Throttle) 12% 12%
Throttle Posn(Full Throttle) 74% 74%
O2 Sensor 1 Bank 1 0.000V 0.000V
Short Term Fuel Trim 1 0% 0%
O2 Sensor 2 Bank 1 0.000V 0.000V
Short Term Trim 2 Not Supported Not Supported


I also did O2 Sensor Tests. 4Runner and T100 numbers were identical

O2 Sensor 1
Low Volt Switch Time 0.400V
High Volt Switch Time 0.550V
Min Sensor Volt 1.275V
Max Sensor Volt 0.000V

O2 Sensor 2
Min Sensor Volt 1.275V
Max Sensor Volt 0.000V

I'm not enough of an ODBII guy to know why the Min Sensor Volt is greater than Max Sensor Volt, but that's what it showed.
I also don't know if there is more data available that my reader cannot access. Again, I'm not knowledgeable enough about ODBII to know.

 

[kgriff]

MAF sensor swapped with T100. No Joy.

I did learn something though. Contrary to the way some of these new-fangled, computer controlled, Pains in the Butt we call cars work, the T100 DID start with no MAF sensor installed. It died right away, but did start. I have experienced some vehicles that will simply crank but not start with a bad MAF.

So, goodie. The 4Runner is still DOA, but I did learn something potentially useful today.

Next up, swap Cam Position Sensor. Yippee. And it's 90+ degrees and I have no shade. Oh Joy.
At least warm weather means my sexy wife is wearing shorts and a tank top. YAY ME!! :happy::happy: