Hello again. Have made a fair bit of progress on this build but have come up aginst a bit of a wall. As the title states I have no CEL which in turn points to the ECU not being powered up hense no spark, fuel Ect. The engine does crank and I have tested every relay and fuse I can find, all proving to be in working order. The ECU ign and ECU B fues are both showing power passing. The one thing that I have found is the wire to the oil level sensor are burnt as if there has been a short circuit at some time. I had completely removed the engine harness and think that this disturbance was the last straw as am only getting 5.8 VDC to the sensor. I have dug pretty deeply into the FSM and have discovered that the ECU can go into a protection mode so the question is. Could the poor signal from the oil level sensor cause the ECU to trigger this protection mode believing that oil level is low and shut down and would the protection mode show the symptoms as described? Even if this is not the root cause of the problem it will be repaired regardless. What do some of you more experienced 80 people think? cheers all Benno
1994 FZJ-80 AU Spec. No CEL. Suspected Electrical Fault.
- Thread starter BennoTVL
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AussieHJCruza
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What's the fusible link like?
Have you tried using the diagnostics box in the engine bay? It needs a really high tech, expensive tool to get it so you can read the code.......a paperclip. 
That will start to tell you more about the power to the ECU, and it will show up if you have power to the ECU as once you have jumped the 2 terminals in there, you will be able to count the Engine Light on the dashboard flashes. With those (or the lack of those) you will be able to work out more of what is happening.
That will start to tell you more about the power to the ECU, and it will show up if you have power to the ECU as once you have jumped the 2 terminals in there, you will be able to count the Engine Light on the dashboard flashes. With those (or the lack of those) you will be able to work out more of what is happening.
If the CEL is not illuminated with the key in the ON position before cranking the starter, the the ECU will not display error codes as it is not in a ready state, or not powered.Have you tried using the diagnostics box in the engine bay? It needs a really high tech, expensive tool to get it so you can read the code.......a paperclip.
That will start to tell you more about the power to the ECU, and it will show up if you have power to the ECU as once you have jumped the 2 terminals in there, you will be able to count the Engine Light on the dashboard flashes. With those (or the lack of those) you will be able to work out more of what is happening.
As previously stated, the first things to check are the 3 fusible links off the positive battery terminal.
A cursory check of all 3 fusible links in system. This assumes an unmolested OEM configuration.
FL AM1 - Dome lights working?
FL AM2 - When you turn the key to ON does the CHARGE LAMP light up?
FL MAIN - Brake lights working?
If yes to all 3, then all 3 fusible links are intact.
I'd read it as there is a problem, it's not working. But it's also not giving me a CEL, not that the the CEL wasn't even coming on!
Very useful trouble shooting in the next post, as I suspect I may need that to help with my BJ70 once I get going on that again (bodywork next...)
AussieHJCruza
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How did you go with the checks from @jonheld above?
Until we've got power to the ECU, not much will happen other than the starter will crank the engine until the battery is dead.
If the fuses are good and the fusible links are good, there's either a short somewhere in the wiring harness or the ECU is dead. Very unlikely the second.
Until we've got power to the ECU, not much will happen other than the starter will crank the engine until the battery is dead.
If the fuses are good and the fusible links are good, there's either a short somewhere in the wiring harness or the ECU is dead. Very unlikely the second.
- Thread starter
- #8
Replaced fuesable link as a matter of course.
- Thread starter
- #9
had previously replaced fuesable links and had tested ok but to be sure I have replaced again with another OEM link. result is the same. All links are passing power.
- Thread starter
- #10
Hi Jon. The answer is Yes to all the points you have made I had previously replaced fuesable links with OEM and it had tested ok but to be sure I have replaced again with another OEM link, result is the same. All links are passing power at 12.46 VDC Current batt voltage.
- Thread starter
- #11
Thanks for the reply, I did make an attempt at code reading but as the ECU is not powering up codes cannot be read.Have you tried using the diagnostics box in the engine bay? It needs a really high tech, expensive tool to get it so you can read the code.......a paperclip.
That will start to tell you more about the power to the ECU, and it will show up if you have power to the ECU as once you have jumped the 2 terminals in there, you will be able to count the Engine Light on the dashboard flashes. With those (or the lack of those) you will be able to work out more of what is happening.
- Thread starter
- #12
did all the checks and all are ok, replaced and tested fueasable links again just in case of a dead new OEM part but still no joy.
- Thread starter
- #13
Thanks to every one who has replied your input is much appreciated.
The Fault as I see it is eigther an open/short circuit within the engine Harness. This I believe because of the identified burnt wires that lead to the engine oil level sensor (replaced OEM as part of engine rebuild).
Finding one pair of burnt wires leads me to believe that there is a good chance that other damage has occoured within the harnes and the discovered damage is only a symptom rather than the root cause.
With this said i think I have 2 options.
1. Remove the engine harnes and begin an exploritory surgery to determain the extent of the damage and repair or replace any damaged wiring within. A job I am capable of but not excited about the prospect.
2. Simply track down a new (not new used) harnes and replace the offending harness whith the hope that my diagnosis is correct and not just throwing good money after bad.
Finally:- If the ECU has gone in a protection mode will it, (once any electrical faults have been repaired), automaticlly reset or is there a manual process for this? Of course the ECU needs to be in working order.
Thanks again benno
EDIT: When I refer to a protection mode I am refering to
2. CONTROL SYSTEM page 55 of ENGINE CONTROL
"QUOTE -4. FAIL–SAFE SYSTEM
WHEN A MALFUNCTION HAS OCCURRED IN ANY SYSTEM, IF THERE IS A POSSIBILITY OF ENGINE TROUBLE BEING CAUSED BY CONTINUED CONTROL BASED ON THE SIGNALS FROM THAT SYSTEM, THE FAIL–SAFE SYSTEM EITHER CONTROLS THE SYSTEMBY USING DATA (STANDARD VALUES) RECORDED IN THE ENGINE CONTROL MODULE (ENGINE ECU) MEMORY OR ELSE STOPS THE ENGINE."
Currently testing that there is power physically reaching the ECU.
The Fault as I see it is eigther an open/short circuit within the engine Harness. This I believe because of the identified burnt wires that lead to the engine oil level sensor (replaced OEM as part of engine rebuild).
Finding one pair of burnt wires leads me to believe that there is a good chance that other damage has occoured within the harnes and the discovered damage is only a symptom rather than the root cause.
With this said i think I have 2 options.
1. Remove the engine harnes and begin an exploritory surgery to determain the extent of the damage and repair or replace any damaged wiring within. A job I am capable of but not excited about the prospect.
2. Simply track down a new (not new used) harnes and replace the offending harness whith the hope that my diagnosis is correct and not just throwing good money after bad.
Finally:- If the ECU has gone in a protection mode will it, (once any electrical faults have been repaired), automaticlly reset or is there a manual process for this? Of course the ECU needs to be in working order.
Thanks again benno
EDIT: When I refer to a protection mode I am refering to
2. CONTROL SYSTEM page 55 of ENGINE CONTROL
"QUOTE -4. FAIL–SAFE SYSTEM
WHEN A MALFUNCTION HAS OCCURRED IN ANY SYSTEM, IF THERE IS A POSSIBILITY OF ENGINE TROUBLE BEING CAUSED BY CONTINUED CONTROL BASED ON THE SIGNALS FROM THAT SYSTEM, THE FAIL–SAFE SYSTEM EITHER CONTROLS THE SYSTEMBY USING DATA (STANDARD VALUES) RECORDED IN THE ENGINE CONTROL MODULE (ENGINE ECU) MEMORY OR ELSE STOPS THE ENGINE."
Currently testing that there is power physically reaching the ECU.
Last edited:
Is the pictured grey plug been reattached??
No batt+ on the yellow/red and no ign+ on the solid red and the ecu won't fire up.
Also check continuity across the plug as I have seen them with crap connections from mud/water exposure.
Also, the pictured motor came drove in with the oil sensor plug busted off and the rear knock sensor wire pulled out, I believe whatever caught and pulled the loom did both at the same time, so they still run without those two.
No batt+ on the yellow/red and no ign+ on the solid red and the ecu won't fire up.
Also check continuity across the plug as I have seen them with crap connections from mud/water exposure.
Also, the pictured motor came drove in with the oil sensor plug busted off and the rear knock sensor wire pulled out, I believe whatever caught and pulled the loom did both at the same time, so they still run without those two.
Probably helps if I attached the picture.
Further to above, I'm thinking there's been no oil sensor for sometime. It was removed for a conversion, due to low power, which, again assuming, was since the knock sensor wire broke.
Further to above, I'm thinking there's been no oil sensor for sometime. It was removed for a conversion, due to low power, which, again assuming, was since the knock sensor wire broke.
- Thread starter
- #16
G'day DUSTandRUST The plug you refer to is connected and does pass pwr.
mudgudgeon
Resident galah
Check the wiring harness connector on the distributor.
If you have a bad pin in it you won't get CEL , and no start
If you have a bad pin in it you won't get CEL , and no start
- Thread starter
- #18
Seems I have 2 accounts here, Not sure how that happened. Repost to this one.
No CEL would crank but no start. I determined that the faults were caused by poor workmanship "by Me". I had inadvertently connected a ground to a +12vdc power source and in doing so created a huge world of hurt for both me and my wallet.
The damage: Burned out engine control harness, damage to the engine bay accessory harness and a fried ECU.
The remedy: I purchase a running rolled over 80, removed all the required parts for the fix and installed all into my project 80.
This has been a roughly 12 month process and I have learned a tremendous amount about the 80 with a lot of great info coming from generous members of this forum so thanks heaps every one.
Finally today I turned the key for the first time in a long time, after a couple of false starts the beast roared to life and ran as if it was brand new again. My most satisfying moment since beginning this build abt 3 yrs ago.
So thanks to every one who made suggestions and everyone that has posted info here.
Happy wheeling, might catch a few bods in the Aussie bush cant wait to get back out there.
Cheers all Benno.
No CEL would crank but no start. I determined that the faults were caused by poor workmanship "by Me". I had inadvertently connected a ground to a +12vdc power source and in doing so created a huge world of hurt for both me and my wallet.
The damage: Burned out engine control harness, damage to the engine bay accessory harness and a fried ECU.
The remedy: I purchase a running rolled over 80, removed all the required parts for the fix and installed all into my project 80.
This has been a roughly 12 month process and I have learned a tremendous amount about the 80 with a lot of great info coming from generous members of this forum so thanks heaps every one.
Finally today I turned the key for the first time in a long time, after a couple of false starts the beast roared to life and ran as if it was brand new again. My most satisfying moment since beginning this build abt 3 yrs ago.
So thanks to every one who made suggestions and everyone that has posted info here.
Happy wheeling, might catch a few bods in the Aussie bush cant wait to get back out there.
Cheers all Benno.
