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Discussion Starter #1
This is a long shot, but here goes. I am looking for somebody in my area with the same truck as mine. I need to test my ECU on a known working Tacoma of the same year and transmission. Even if you're as far as 2 hours away, Ill still come to you. Yes, I will pay you for your time.



Long story short, I bought an Ebay ECU that the seller claimed was 'tested', but I don't believe it. I did this trying to change my no spark situation, but it did not help. I still believe the ECU is at fault after changing everything down to the wiring harness.
 

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Have you tried seeing if one of the parts yard near you might have yer ECU? Is yer vehicle 2WD or 4WD? What month/year was it made? What is the part number on yer ECU? ;)

From www.car-part.com... ;)
Electronic Control Module, (RH dash), 4x2, from 6/97, 4 cylinder, MT
Electronic Control Module, (RH dash), 4x2, thru 5/97, 4 cylinder, MT
Electronic Control Module, (RH dash), 4x4, from 6/97, 4 cylinder, MT
Electronic Control Module, (RH dash), 4x4, thru 5/97, 4 cylinder, MT
What issues are you experiencing that you are suspecting the ECU? ;)
 

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Discussion Starter #4 (Edited)
I have an impossible to fix problem, no spark, no matter what I do, no matter what I've replaced, nothing changes. I had a bad original ECU (so I thought), so I bought another ECU off ebay from a junkyard seller. The guy claims it was a working ECU, but I cant verify that. I guarantee he never saw the truck that the ECU was in, or running. Anyway, I trusted him, so I thought if he tested the ECU, it has to be something else. Hence I started throwing parts at it. I'm done testing and trying to diagnose this. I think this last request for somebody with a similar truck is the last thing I'm going to do before I have the truck hauled away.

Yes, thats the reference thread. And another to add to it:


https://www.scannerdanner.com/forum/post-your-repair-questions-here/4183-1997-tacoma-2-4-no-spark-no-start-can-t-solve-impossible-fix.html?start=0



ECU #

1997 Toyota Tacoma Pickup Engine Computer ECU 2WD M/T 2.4L / ECU Number 89661-04240
 

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What is the month/year of manufacture? It should be on the VIN plate off of the door jamb. ;)

Have you pulled the crankshaft sensor and checked to see if the toothed gear is moving or in place? ;)
 

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As you can tell by this piccie, the gear has a slot fer the shaft key to index into. If the key is sheared off, you can replace the key without any issues. However, you will need to pull the crankshaft pulley and crankshaft gear off in order to replace the key. ;)

Here's the part number fer the crankshaft position sensor rotor. Current online discount is around $25 or so. ;)
19315A
ROTOR, CRANK POSITION SENSOR
19315-75010
1
$28.27

Here's the part number fer the key. ;)
13521A
KEY(FOR CRANKSHAFT TIMING GEAR)
90280-05005
1
$1.30

Here's the part number fer the timing gear. ;)
13521
GEAR OR SPROCKET, CRANKSHAFT TIMING
13521-75010
1
$60.69

Have you verified that yer timing gear/chain is moving? The key fer the crankshaft position sensor rotor is the same fer the timing gear so if that key is broken neither the timing gear or rotor will turn. ;)

Are you sure yer willing to let yer truck go fer less than $30 in parts? ;)
 

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There is something to note with the chain driven 2rzfe engine. It is considered an interference engine. If the chain or key is broken, chances are that yer valves stand a good chance of being damaged. Have you performed a compression test? It would be a quick way of determining if the timing chain is indeed intact and working. Another quick way would be to remove one of the spark plugs and plug the hole with a rag. Crank the engine. The compression should blow the rag out. If it doesn't, yer not gitting compression in the cylinder. ;)
 

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Discussion Starter #9
There is something to note with the chain driven 2rzfe engine. It is considered an interference engine. If the chain or key is broken, chances are that yer valves stand a good chance of being damaged. Have you performed a compression test? It would be a quick way of determining if the timing chain is indeed intact and working. Another quick way would be to remove one of the spark plugs and plug the hole with a rag. Crank the engine. The compression should blow the rag out. If it doesn't, yer not gitting compression in the cylinder. ;)
Weve got plenty of compression, and the chain is intact and rotating the camshaft. Now, here's the mystery and why I thought this was not mechanical; the truck died twice in a few months apart (no start situation, no spark) and restarted on its own after sitting. I thought it wasn't a significant issue until it died a third time and wouldn't restart. That's where were at now. So, that's why I suspect that its not the timing gear wheel, but I could be completely wrong. If that key sheared, it wouldn't be an intermittent problem, just completely dead.
 

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Have you verified that the rotor is in fact moving and not detached? You should be able to pull the crankcase sensor and use a screwdriver in the hole to see if the rotor will move or not. ;)
 

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The shotgun approach is never as effective as it is costly.


Besides the ECU and a wiring harness, what have you replaced? What diagnostics have you done? Is it injecting fuel?


It's unlikely IMO that both ECUs would have the exact same failure mode. I also doubt that both of them are bad or that the original even was.
 

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Discussion Starter #12
Have you verified that the rotor is in fact moving and not detached? You should be able to pull the crankcase sensor and use a screwdriver in the hole to see if the rotor will move or not. ;)
The timing wheel is attached and not sheared. I used an endoscope camera to verify this.
 

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Discussion Starter #13
The shotgun approach is never as effective as it is costly.


Besides the ECU and a wiring harness, what have you replaced? What diagnostics have you done? Is it injecting fuel?


It's unlikely IMO that both ECUs would have the exact same failure mode. I also doubt that both of them are bad or that the original even was.
I've done every diagnostic that you can do without an oscilloscope (I'm limited to a multi-meter and a test light). Everything got power and communicating with the ECU, and the ECU is communicating back to everything. I am absolutely stumped on this one, my first failure to diagnose or fix a vehicle!
 
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