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Old 12-02-2019, 06:49 PM   #1
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Default 1986 Nissan King Cab SE (4X4 MT VG30) aka Desert Kitten

Hey all, acquired this truck from an acquaintance.

It hasn't been running in about 5 years. I went through the whole fsm procedure for diagnosing no spark back to the ECU, which I'm finding doesn't turn on. Checked voltage at the pins and locations in the fsm but came back to poor fusible links (I went through and resoldered new fusible link wire into the main link), a break in harness (but didn't I check voltages and confirm this isn't the case? Yes), or bad ECU. Still no power on the ECU. Is there anything I'm missing here? PO threw new coil, cap& rotor, etc at it prior to giving up and parking the truck.
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Old 12-02-2019, 07:16 PM   #2
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ECU ground.
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Old 12-03-2019, 05:04 PM   #3
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Quote:
Originally Posted by dvdswan View Post
ECU ground.
How can I check this? Should I grind out a new spot to ground the ECU to? I was not using the ECU ground when checking v+ on the harness plugs
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Old 12-03-2019, 11:50 PM   #4
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Where the ECU is under the passenger seat there is a ground to the hump that the seat bolts to. That has a tendency to get rusty/corroded.
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Old 02-27-2020, 01:06 AM   #5
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So just getting back to this heap and trying to diagnose,

Seems the ground has no effect on getting the eccs module (aka ecu) to light up. I have the ground wire going to the passengers side most mounting arm on the ecu casing, I assume this is sufficient, as there's no specific mention in the manual...

I think I am going to bite the bullet and buy a reman ecu from oreilly soon and see where that gets me.
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Old 02-27-2020, 07:21 PM   #6
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The computer ground attaches to the pass side mounting tab on the box so seems you have that right. You haven't been clear as to whether power is getting to the ECU or not. Are you getting power to the ignition switch? Any power anywhere when key is turned on? You reference the FSM so I assume you've looked over pg EF-EC 82 outlining the power source to the ECU, and also EL 100 which shows the location of the fusible links and the main relay. You've checked voltage at the computer harness at the proper pins and, nothing? If power is not getting to the ECU then you have a blown fusible link, bad main relay or bad ignition switch. Or you have some serious harness damage somewhere or something is disconnected. If power is getting to the ECU then we can rule this out and start from there.

Has the computer case, or lid, been taken off and reassembled? I once had a situation where I took the top of the case off and looked around, then put it back on. Thereafter I had an issue where the truck would die every time I went over a bump. I took the ECU back out of the truck and found that one of the lid tabs had folded under when I reinstalled it and It was grounding out the fuel pump circuit. Long shot I know but maybe something to check.

Personally I would nab a junkyard ECU or check ebay before blowing several hundred on a reman.

EDIT - I just checked eBay, ouch. I guess prices on these things have skyrocketed in the last few years. Well, id still try to hit up the JY. $50 at the LKQ if you can find one.

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Old 02-28-2020, 04:09 PM   #7
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I have checked power at the ecu, replaced the fusible links, and there is a new ignition switch installed (PO threw a bunch of parts at it but never seemed to get the ecu going) but still haven't seemed to get anything... I wouldn't normally want to spend this much without more certainty, but this thing is coating me money sitting being insured and I would rather be able to drive it than not!

I tried to buy one on eBay but they cancelled my order before they shipped the item and told me they couldn't find the ecu in the truck...

No srw 3.0 MT 4x4 trucks around here go pull an ecu from!!
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Old 02-28-2020, 07:19 PM   #8
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SRW or DRW doesn't matter. Just gotta be a V6 truck. I believe the autos have a separate TCM.
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