Solved: Electrical help - 4wd wont engage after H55F swap on FJ62 (1 Viewer)

EscapeWagon62

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Any help on electrical appreciated.
Background
Just completed an H55 swap on my FJ62, It still has the original vacuum operated transfer case. We can start and drive.

Admission:
We mis-wired on our first attempt and blew the wiper motor fuse. Our “expert” assistant” jumped it the fuse as he was was testing and we melted a wire on the passenger side footwell. Right below a switch I’ll cover below. We caught it quickly but I have a feeling this has something to do with our transfer case not activsting.

What we have confirmed:
We have vacuum and even tried reversing the two vacuum ports with zero effect.
We do not have any weird noises in the transfer case, it just doesn't react at all.
We cannot get the transfer case 4WD indicator to set off the 4wd light in the dash. We pulled it out, while attached to its harness and powered and manually pushed the ball to activate it. Nothing. We pulled it out and off the wiring harness and tested on the workbench and the switch is good.

My assumption is that we either:
A) Still have an electrical mis-wire
B) We blew the transmission switch located in the passenger footwell.
C) Other?

photo of switch attached
Any advice appreciated.

ED3BA548-6CCC-494D-8F40-2FE5488A1A3C.jpeg
 
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What vacuum ports did you reverse specifically? Supply direct vacuum to either hose going to the tcase and see if you can get engagement, skipping the solenoids completely.

Are you sure the lines are connected at the tcase?
 

EscapeWagon62

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What vacuum ports did you reverse specifically? Supply direct vacuum to either hose going to the tcase and see if you can get engagement, skipping the solenoids completely.

Are you sure the lines are connected at the tcase?
I’ll try applying vacuum directly. We tried it both at the solenoids and at the transfer case but didn't try direct vacuum.
Possible thst I have a vacuum leak but it wont explain the 4WD indicator not illuminating even when the switch is manually pressed while connected to the harness.
I’ll try anything and everything 👍. Thank you
 
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I’ll try applying vacuum directly. We tried it both at the solenoids and at the transfer case but didn't try direct vacuum.
Possible thst I have a vacuum leak but it wont explain the 4WD indicator not illuminating even when the switch is manually pressed while connected to the harness.
I’ll try anything and everything 👍. Thank you

If you have known good vacuum to the actuator and apply it on one of the two ports, the front driveshaft should engage. If it doesn't, you may have two problems.


Obviously applying vacuum to both ports at the same time will do nothing.
 
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Does the manual linkage to 4 Low work and actuate the tcase into 4WD?

If you can't get it into4 Low then you have a problem mechanically with the tcase (ie ball detent fell down when you installed the shift fork).


Do you have the factory service manual and the electrical diagrams?
 

EscapeWagon62

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@Randy88FJ62
I’ll do a manual check on 4wd engagement via removing the vacuum activator first.
I do have an FSM and electrical diagram. We were chasing that and will get back after it tomorrow.
Are you referring to the fork in the main housing that switches hi/low or the fork in the front flange that engages the front shaft?
 

EscapeWagon62

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Thank you. I’ll have to wait for my son to come home as he was the electrical person on this.
Stay tuned on that.
I can engage low gear but it only spins rear wheels. I just haven’t been able to get 4 wheel high or low to engage.
What’s baffling me is that the switch pictured below, which I believe is the one that would activate the 4wd light does not activate the light when pulled out while attached to the harness but does pass electrical bench test.
The whole system worked perfectly before the swap so I’ve either botched the wiring, botched assembly of the transfer or both.
I’ll try to provide some detail to,orrow.
thanks again

Adding this diagram to help us all understand what electrical parts you have and have not checked:

View attachment 2525588

EEB4F48B-85D2-4186-BFDC-CEA457BC4B81.png
 

EscapeWagon62

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The light doesn't come on until the case actually shifts for the record.
Yes, I could have been clearer on that. We tried in gear on a lift and drove it on the road.
W did test the solenoids, dash switch and 4wd dash switch and all are operational.
Just in case we ended up with a vacuum leak to to uninstall and reinstall....I'll swap out the lower vacuum lines tomorrow. The ones at the Solenoids are new as of a year ago.
 
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If you cannot mechanically shift into 4 low then you need to look at the transfer case.

Where it gets fuzzy for me is if the vacuum front end needs to be engaged and I think that is where we need someone with more knowledge as I haven't messed with that in years.

@cruisermatt?
 

EscapeWagon62

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Since I know I can shift to 4wd low and experienced a vacuum leak driving home, I’ll swap out the two soft lines today going into the transfer case vacuum diaphragm
My bet is that is my issue since the solenoids are working
I’ll update soon
I think I was tired, frustrated and not thinking clearly
If that doesn’t handle it, then I screwed up the wiring and or the transmission switch in the passenger footwell. I have a replacement inbound
Fingers crossed
 

cruisermatt

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the H55f swap wiring shouldn't have anything to do with the Vacuum shift electrical logic, if it worked before it should work again after, so you did something wrong.
Why did the wiper fuse blow??
What is this about the transmission switch?
If you look in the FSM schematic (Which you should do before starting a thread like this) you would see that the transmission wiring is completely independent of the T-case.
 
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EscapeWagon62

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Wiper fuse blew when we connected the reverse lights to the wrong wire.
We got that sorted out after reading a few more threads.
4wd worked before so I think its vacuum. I was just so worn out that my brain went into idiot lock last night.
I’ll take another crack at it with fresh vacuum lines today.

I really loved driving home in a stick shift Last night. What a change!
 
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Yesterday you said, " I can engage low gear but it only spins rear wheels".

There is a mod on the forums where you can take the shift plate off under the transmission hump and it allows you to shift into 2Lo instead of 4Lo. This is something you should be aware and verify independent of the vacuum lines and electrical.
 

EscapeWagon62

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Yesterday you said, " I can engage low gear but it only spins rear wheels".

There is a mod on the forums where you can take the shift plate off under the transmission hump and it allows you to shift into 2Lo instead of 4Lo. This is something you should be aware and verify independent of the vacuum lines and electrical.
My apologies for the confusion. I can shift the transfer case between high, neutral and low without issue. and drove it to confirm low gear. My issue was just the front drive shaft engagement. This case isn't modified and worked as factory prior to the swap.
Hope to have successful report back by this weekend.
 

cruisermatt

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Yesterday you said, " I can engage low gear but it only spins rear wheels".

There is a mod on the forums where you can take the shift plate off under the transmission hump and it allows you to shift into 2Lo instead of 4Lo. This is something you should be aware and verify independent of the vacuum lines and electrical.

This would only be true on a manual shift case. Not a vacuum shift case
 

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