I goofed up my ECM repair…

[Sparkxy]

So for some background I’ve been having the following issues with my prado and I’ve been chasing ghosts only to find out there was bad caps on the ECU
Car would have solenoid #1 malfunction intermittently putting transmission into fail safe mode, flashing O/D and spat out DTC 64,62

1. Measured resistance of solenoid #1 per Toyota worshop manual (12ohms)
2. Engine would cut power at any speed intermittently,pull and reseat fuse to reset ecm and would work fine but still would randomly cut power whenever it felt like it.
3. P, D light on instrument cluster would randomly hard cut in/out. More often with P, rarely with D
4. Glow plug light would not illuminate on first start, cycled power and would illuminate (sometimes)

1. Disassembled ecm to inspect capacitors and found 2 leaky caps damaging traces next to chip 151805-1811. Cleaned out oxidized capacitor pads and tinned with new solder. Effected capacitors C014 and C004.
2. Replaced 220 uf 10v C014 with 220uf 25V capacitor
3. Replaced C004 100uf 10v capacitor with 100uf 25v capacitor
4. Continuity checked effected traces on chip 151805-1811, cleaned with isopropyl alcohol and tinned with solder. (00.3ohms) measured on repaired traces

1. Found leaky capacitor C001 and replaced 33uf 35v with 3x 100uf 16v put in series to make 33.3uf 48v capacitor. Just didn’t have a 33uf cap on hand with correct voltage rating, figure higher voltage would be safer long term
2. Could not find room on top of board, installed underneath and insulated with aircraft insulating tape.

1. Installed ecm onto land cruiser
2. Engine would crank no start.
3. Bled fuel line manually with vaccum tester hooked onto lift pump output. After first failed crank, opened injector 1 to see if fuel was reaching injector. No fuel present on subsequent crank attempt.
4. Known issue is suspect lift pump. Installed check valve onto lift pump supply line and would vaccum bleed manually via lift pump output line. Vaccum pressure would not hold.
5. Attached DLC3-OBD adapter to tactrix openport with pass through interface driver
6. Launched Toyota techstream V18 with correct VIM set to openport
7. Connected to tactrix openport through Toyota techstream but would not pull information from ECU.

Information

car spec: JDM 1996 Land Cruiser prado 90 4speed automatic

Engine: 1KZTE 3.0TD w/ top mount intercooler

ECM part no: 89601-60520

 

[KiwiBogan]

Geez, sounds like a whole heap of fluffing about when you could have just bought a 2nd hand ECU from a wrecker for $200!

Assuming you've fixed the ECU now, have a look into the Spill Control Valve on the back of the Inj pump. When I bought my Prado, it had a "crank but no start" issue. I chased it down to the SCV being sticky/seized. I was able to free it up by removing the SCV from the injector pump (being VERY careful not to let dust or debris get into the IP!). I cleaned the stainless steel mesh filter at the bottom of the valve with acetone. (Take note of the direction this filter sits underneath the SCV as it may or may not come out with the SCV and you might need to use tweezers to fish it out of the pump). I then applied 12v pos & neg directly from the car battery to the terminals on the SCV, on and off in quick succession about 20 times. You'll hear the solenoid inside click as you do this. I then placed the SCV back into the IP. Primed the system with the hand pump on the fuel filter housing until firm. Preheated glow plugs for 10 seconds and within a couple of turns, the car finally jumped to life. It started in half a turn thereafter.

Maybe before you go through all this, pop a multi meter on the plug that plugs into the SCV first. Turn the engine over and see what it reads. From memory is supposed to be anything from 9v to 14v across those two wires. Mine was reading 10v from memory. That might also give you a clue if the ECU isn't sending a signal to the SCV.

Good luck with it!

 

[Sparkxy]

Geez, sounds like a whole heap of fluffing about when you could have just bought a 2nd hand ECU from a wrecker for $200!

Assuming you've fixed the ECU now, have a look into the Spill Control Valve on the back of the Inj pump. When I bought my Prado, it had a "crank but no start" issue. I chased it down to the SCV being sticky/seized. I was able to free it up by removing the SCV from the injector pump (being VERY careful not to let dust or debris get into the IP!). I cleaned the stainless steel mesh filter at the bottom of the valve with acetone. (Take note of the direction this filter sits underneath the SCV as it may or may not come out with the SCV and you might need to use tweezers to fish it out of the pump). I then applied 12v pos & neg directly from the car battery to the terminals on the SCV, on and off in quick succession about 20 times. You'll hear the solenoid inside click as you do this. I then placed the SCV back into the IP. Primed the system with the hand pump on the fuel filter housing until firm. Preheated glow plugs for 10 seconds and within a couple of turns, the car finally jumped to life. It started in half a turn thereafter.

Maybe before you go through all this, pop a multi meter on the plug that plugs into the SCV first. Turn the engine over and see what it reads. From memory is supposed to be anything from 9v to 14v across those two wires. Mine was reading 10v from memory. That might also give you a clue if the ECU isn't sending a signal to the SCV.

Good luck with it!

I am so dumb, I’ve been chasing circuit issues (being an avionics tech by trade) when I should’ve been chasing fuel issues this whole time. Thank you man, I really appreciate it. I’ll keep this updated. I do my best to methodically isolate issues and figured if I couldn’t get communication with the ecu via techstream as a way to “bench check” to see if I did everything correctly.

 

[KiwiBogan]

Well if you're ECU caps are leaking, that's priority #1. To be honest, as an amateur DIY electronics enthusiast with an insatiable desire to know how things work and to be able to fix them myself, I totally would have butchered that board having a crack at fixing it myself, before realising I should have just bought a used one and called it a day lol. But yeah, from there, you need to obviously test to see the sensors are receiving signal from the ECU.

Not being able to connect to the ECU with an OBD2 reader is not a good indication of ECU functionality. Some Bluetooth dongles available and generic scanners just don't work for some reason beyond my care to troubleshoot much further. Attached is a pic of two typical ELM327 dongles. The taped up one works on my 2000 Prado and a work makes 2001 Prado with 1KZs. The clean looking one doesn't work on either. My taped one also works on my old Ford Transit and a 2014 Ford Ranger PK I'm currently driving for work.

So if you're using a Bluetooth dongle, try a few different types. They're all cheap as chips on eBay etc so you just gotta try and find one that works.

Also I use a phone app called ELMScan Toyota. It's hard to find now. You'll have to dig around.

 

[Sparkxy]

Well if you're ECU caps are leaking, that's priority #1. To be honest, as an amateur DIY electronics enthusiast with an insatiable desire to know how things work and to be able to fix them myself, I totally would have butchered that board having a crack at fixing it myself, before realising I should have just bought a used one and called it a day lol. But yeah, from there, you need to obviously test to see the sensors are receiving signal from the ECU.

Not being able to connect to the ECU with an OBD2 reader is not a good indication of ECU functionality. Some Bluetooth dongles available and generic scanners just don't work for some reason beyond my care to troubleshoot much further. Attached is a pic of two typical ELM327 dongles. The taped up one works on my 2000 Prado and a work makes 2001 Prado with 1KZs. The clean looking one doesn't work on either. My taped one also works on my old Ford Transit and a 2014 Ford Ranger PK I'm currently driving for work.

So if you're using a Bluetooth dongle, try a few different types. They're all cheap as chips on eBay etc so you just gotta try and find one that works.

Also I use a phone app called ELMScan Toyota. It's hard to find now. You'll have to dig around.

View attachment 3667658

I did what you said and yeah ur right, I’m just gonna shotgun a new ecu from a guy locally. Fingers crossed the caps are good and no traces are screwed.He’s suppose to send me a pic in a few so we’ll see the extent of potential damage I'm just gonna order the correct caps for this new one as a precaution this time. Other than that I’m just gonna shoot the spill control valve and test all the relays to see if anything funky is happening downstream of the spill control valve itself. Should be pretty straight forward. Just concerned about the spill control valve itself as you described actuating it to “unstick”. Is this just a temp fix or something that will hold up long term. The spill control valve looks kinda pricey for basically a run of the mill solenoid with a special housing. Thoughts?

 

[KiwiBogan]

I did what you said and yeah ur right, I’m just gonna shotgun a new ecu from a guy locally. Fingers crossed the caps are good and no traces are screwed.He’s suppose to send me a pic in a few so we’ll see the extent of potential damage I'm just gonna order the correct caps for this new one as a precaution this time. Other than that I’m just gonna shoot the spill control valve and test all the relays to see if anything funky is happening downstream of the spill control valve itself. Should be pretty straight forward. Just concerned about the spill control valve itself as you described actuating it to “unstick”. Is this just a temp fix or something that will hold up long term. The spill control valve looks kinda pricey for basically a run of the mill solenoid with a special housing. Thoughts?

It's quite unusual what happened to your ECU with theeaky caps. Theirs a couple of instances of it happening around the web but I think it's way less common than you might think. The only thing I can think of how that might have caused it is the battery being reverse wired or some extremely stupid event like that haha. Mayyybe a water crossing or failed alternator spiking the system but I'm pretty sure their are fuses in place to prevent such catastrophic issues. My ECU when I opened it was fully sealed and looked as new as the day it was made! (Again this is on a 2000 model which had a hard life).

Re the SCV, no it was a long term fix! I got the car cheap as the seller thought the fuel pump was knackered. All the "specialists" I spoke to (3 of) about it agreed the injector pump was knackered and needed replaced. My fix above not only fixed the car but made it drive HEAPS nicer. Lasted a few years up until recently when I got rid of the car, it was still running perfectly. I even had a Unichip installed and was running the pump at higher capacity than stock, no dramas.

 

[Sparkxy]

It's quite unusual what happened to your ECU with theeaky caps. Theirs a couple of instances of it happening around the web but I think it's way less common than you might think. The only thing I can think of how that might have caused it is the battery being reverse wired or some extremely stupid event like that haha. Mayyybe a water crossing or failed alternator spiking the system but I'm pretty sure their are fuses in place to prevent such catastrophic issues. My ECU when I opened it was fully sealed and looked as new as the day it was made! (Again this is on a 2000 model which had a hard life).

Re the SCV, no it was a long term fix! I got the car cheap as the seller thought the fuel pump was knackered. All the "specialists" I spoke to (3 of) about it agreed the injector pump was knackered and needed replaced. My fix above not only fixed the car but made it drive HEAPS nicer. Lasted a few years up until recently when I got rid of the car, it was still running perfectly. I even had a Unichip installed and was running the pump at higher capacity than stock, no dramas.

Couldn’t get that damn spill control valve out. Just used 12V from the battery and switched it 20 or so times but still nothing. Still crank no start, no fuel coming out from the injectors either. I’m guessing test the ecu pins for the SCV actuation or what?

 

[KiwiBogan]

Couldn’t get that damn spill control valve out. Just used 12V from the battery and switched it 20 or so times but still nothing. Still crank no start, no fuel coming out from the injectors either. I’m guessing test the ecu pins for the SCV actuation or what?

Is there fuel getting to the pump? Have you pumped the hand primer till it's firm?

It does sound like an ECU problem though. I'd honestly try and source one from a wrecker and give it a try. Otherwise you could be chasing your tail forever on this. Another thought... Does the red door + key immobilizer light extinguish from the dash once you turn the ignition on? I doubt it is this but could be a problem with the immobilizer which would result in a crank but no start scenario. Had this happen to me once. Discovered the immobilizer plug had disconnected from the blade on the side of the ignition barrel. It looked like it was connected but wasn't making contact. I must have knocked it out when messing around with wiring under the dash.

 

[Sparkxy]

Is there fuel getting to the pump? Have you pumped the hand primer till it's firm?

It does sound like an ECU problem though. I'd honestly try and source one from a wrecker and give it a try. Otherwise you could be chasing your tail forever on this. Another thought... Does the red door + key immobilizer light extinguish from the dash once you turn the ignition on? I doubt it is this but could be a problem with the immobilizer which would result in a crank but no start scenario. Had this happen to me once. Discovered the immobilizer plug had disconnected from the blade on the side of the ignition barrel. It looked like it was connected but wasn't making contact. I must have knocked it out when messing around with wiring under the dash.

Ok I figured it out. My dumbass didn’t connect one of the bulkhead connectors right above the ECU. Thing fired to life. Made sure all the pins and plugs were in after and I’ve been running flawlessly

 

[Rawloh44]

Ok I figured it out. My dumbass didn’t connect one of the bulkhead connectors right above the ECU. Thing fired to life. Made sure all the pins and plugs were in after and I’ve been running flawlessly

Congrats on getting it to fire up, but do you have a source for a spare ECU?

 

[OM617YOTA]

It's quite unusual what happened to your ECU with theeaky caps. Theirs a couple of instances of it happening around the web but I think it's way less common than you might think. The only thing I can think of how that might have caused it is the battery being reverse wired or some extremely stupid event like that haha. Mayyybe a water crossing or failed alternator spiking the system but I'm pretty sure their are fuses in place to prevent such catastrophic issues. My ECU when I opened it was fully sealed and looked as new as the day it was made! (Again this is on a 2000 model which had a hard life).

Re the SCV, no it was a long term fix! I got the car cheap as the seller thought the fuel pump was knackered. All the "specialists" I spoke to (3 of) about it agreed the injector pump was knackered and needed replaced. My fix above not only fixed the car but made it drive HEAPS nicer. Lasted a few years up until recently when I got rid of the car, it was still running perfectly. I even had a Unichip installed and was running the pump at higher capacity than stock, no dramas.

No clue about Prado ECUs, but electrolytic caps leaking is pretty common, and VERY common with caps from a certain era. Look up "capacitor plague".

Capacitor plague - Wikipedia

en.wikipedia.org

 

[Sparkxy]

Congrats on getting it to fire up, but do you have a source for a spare ECU?

She’s been running good for the past months with no issues, I should look into a spare ECU just in case but haven’t had the time to source one as of yet

 

[Rawloh44]

She’s been running good for the past months with no issues, I should look into a spare ECU just in case but haven’t had the time to source one as of yet

I was lucky enough to find capacitor leaks early, barely any damage to the board where i only had apply shielding to one section, only 2 were leaking, but replaced all thankfully, i have not had issues since