New engine harness, now won’t start

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If my NSS isn’t seeing any power, how are my turn signals, wipers, etc working?
How are you checking for power?

If I'm understanding the diagram correctly, you should be seeing ~12V on the black/white wire only with the ignition in the 'start' position.

You should see ~12V on the black wire with the ignition in the 'on' or 'start' positions.

The fuse block is powered by several wires:

94EWD-PowerSource-p48.png
 

TomH

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The chart you posted shows where each source gets its power. All of the sources you are asking about get their power from FL AM1 - AM1. The path to each source is separate. You've already confirmed power to AM1.

This snip from the Power Source page shows AM1 goes to the ignition switch and then IG1 distributes the power to the fuse box.

1668568521614.png


I posted the wrong drawing of IH1 previously. Here is the correct one and it is the big one in your picture. Pin 21 is the large B-W wire in front next to the big Y wire.

1668569095241.png


Looks like I was wrong again and IH1 is connected.

Next thing to check is whether you have 12V to pin 21 (B-W wire) with key to start. You should be able to get the meter probe in the back of the connector without disconnecting. This is where the NSS gets the power that is sent to pin 5 on the NSS, which you say has no power.

1668569564890.png


How did you check for power at Pin 5 on NSS?
 
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alia176

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I wonder if the NSS is suspect?

I'm just curious, what are y'all paying for an ECU harness these days?
 

TomH

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Ok, was able to check pin 21 on IH1 in the start position and I’ve got 12V. So…wtf
If it were me I'd keep working down the circuit. At this point I'd probably pull the connector on the starter and check for 12V at the starter with key to start. If you have 12V there then your starter is probably bad, as has been suggested by a couple people. If you don't then you are back to the NSS.
 

whitey45

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Jump power to your solenoid to rule out your starter? Like others have said, its going to be a simple fix that was somehow overlooked.
 
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Ok, was able to check pin 21 on IH1 in the start position and I’ve got 12V. So…wtf
Did you check the black/red wire coming out of the NSS?

If your NSS is adjusted wrong or faulty, it's not going to pass current. It's supposed to pass current to the starter only in Park and Neutral.

94EWD-StartIgnition.png
 
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I think you guys are right and it’s something simple that I overlooked. I would say it’s not the NSS but it was gunked up and then removed to be cleaned so now it’s totally possible that could be it. I’ll check the starter for power and back to the NSS tonight hopefully. Wish it was off today to troubleshoot this in the daytime
 

TomH

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Checked pin 6 on the NSS with key to start and I’m getting no voltage at all. I have a new fusible link coming in today so I’ll be able to rule that out but I don’t think that’s the issue anyway.

Ok, was able to check pin 21 on IH1 in the start position and I’ve got 12V. So…wtf

I was looking back at this because I thought you checked pin 5 on the NSS but you did check pin 6.

This means:
You checked for power incorrectly at pin 6 of the NSS connector. Did you check on the NSS or the connector going to the NSS? You should unplug the connector and check for power at the connector.
The wire between IH1 and NSS is open, i.e. broken. The wire is a direct path from IH1 to P1 (NSS). If you have power at IH1 then you should have power at P1.

1668788358441.png
 
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ToyotaMatt

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I printed this from the electrical service manual yesterday to check but I hate this daylight savings junk. The truck is in my driveway and I don’t want to mess with it when I get home from work and it’s already dark. Gonna have to suck it up and check that circuit. I think you’re definitely right.


how many days spread out did the new harness install take ?

1 day


6 sundays in a row ?


curious , this can play a fatcor
 
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how many days spread out did the new harness install take ?

1 day


6 sundays in a row ?


curious , this can play a fatcor
1 day. I had the harness out and back in the same day. Finished connecting everything the next day but it was in place the same day and I ran out of light. I did check pin 6 at the connector unplugged from the NSS. So do I need to do the same but pin 5 instead?
 
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Ok, update…I’m not getting any power at pin 5 on the NSS connector nor am I getting power at the starter. However…I gave direct power to the starter with the key on and the truck runs.
I don’t understand how I’m not getting any voltage at the NSS connector with power at IH1 but at least the truck is capable of running
 

TomH

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Do you have power at pin 6 of the NSS connector with key to start? How did you check for power?
How did you check for power at pin 5 of the NSS connector?
Is the NSS connector part of the engine harness you replaced?
 
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I don’t understand how I’m not getting any voltage at the NSS connec

Because it's either adjusted wrong or faulty. It's my understanding that if you're seeing voltage on the black/white wire, but it's not coming out on the black/red wire, then the fault has to be in the NSS.

Have you disassembled the NSS to clean it?

LC97FSM-DI-171-Diagnostics.png
LC97FSM-AT-7-ParkNeutralPositionSwitch.png
LC97FSM-DI-143-ParkNeutralPositionSwitchAdjustment.png
 
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I understand the NSS could be faulty or not adjusted correctly but I’m not seeing any voltage at pin 5 or 6 on the harness at that connected to even give power to the NSS itself. That connected is part of the engine harness I changed out. Testing for power the way I did at all other connections…red lead into the specific pin on the connector and grounding the black.

A0883B95-77A6-43A2-8756-6910159CB5FE.jpeg


Tried several ways of grounding to be sure even grounding to the negative battery terminal with the black lead of a set of jumper cables. Can’t probe the back of the connector as it has those rubber seals on the back. Also, before testing for power at the starter + connector, I did connect the harness back to the NSS (which wouldn’t matter if it’s adjusted wrong I assume)

So, please tell me I’m testing for power wrong like a total idiot or missing something simple
 
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Looking at that last diagram you sent, Gummy, there’s no way I shouldn’t have power at pin 5 or 6 on that NSS connector. Is it possible I could have a bad or worn out ignition switch? Is that a dumb question?
 

TomH

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Testing for power the way I did at all other connections…red lead into the specific pin on the connector and grounding the black.

You can't test for power at pin 5 of the NSS that way. Pin 5 gets its power from pin 6 through the NSS so the connector would need to be hooked up. You only get power to pin 5 if the shifter is in neutral or park, that is what prevents you from starting in gear. However, if you don't have power to the starter then you most likely don't have power at pin 5. It does go through splice E19 but not likely the problem.

If you are confident you ARE NOT getting power at pin 6 of the NSS and you are confident you ARE getting power to IH1 pin 21 then I say your harness is bad. There is a direct path from IH1 to NSS. Is IH1 part of the engine harness?

This snip of the diagram shows and direct path from IH1-21 to P1-6. Power should be pin to pin.
This snip also shows that pin 5 gets power from pin 6 by going through the NSS when shifter is in park or neutral.

1668955913004.png


I think the next thing I would do is check the continuity from IH1-21 to P1-6 just to confirm it is bad.
 
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TomH

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Looking at that last diagram you sent, Gummy, there’s no way I shouldn’t have power at pin 5 or 6 on that NSS connector. Is it possible I could have a bad or worn out ignition switch? Is that a dumb question?

If you are getting power at IH1 then the ignition switch is good. Power goes through the switch to get to IH1.
 

TomH

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Where is the rest of the black/white wire in your picture? Looks like it is missing/cut.

Edit - could just be the picture, maybe it is going behind the orange wire.

1668955594237.png
 
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The black and white wire under the dash is just hiding behind that orange wire. I just checked pin 6 on the NSS connector again and I do in fact have 12V like I should.
 

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