LJ78 mystery connector (1 Viewer)

[Cascadia]

Hi guys. I can’t believe I’m posting such a simple question but I’m a little stumped.

I’m reinstalling my engine and there’s a female connection on my wiring harness I’m stuck on. Every other connection has been painfully obvious and I’m feeling foolish here for not seeing the male counterpart to this.

Round black plugs in to my alternator, small grey plugs into my A/C compressor, but what about the third one?

 

[Nas90tdi]

I can look later to verify. But, I believe that is the vacuum sensor on the air filter inlet.

 

[Cascadia]

I was thinking that, but if we’re thinking of the same connection I don’t think it’s the one. The one on my air cleaner is accounted for.

 

[Gengis]

My HZ has a plug for a rev counter in the loom, but no pick up in the IP, so it hangs loose.
Could this be your problem??

 

[AirheadNut]

To me that looks like the plug for the factory “sport” shock absorber, page 46 in the wiring manual. I might be mistaken, but I can check mine in the morning.

 

[Cascadia]

To me that looks like the plug for the factory “sport” shock absorber, page 46 in the wiring manual. I might be mistaken, but I can check mine in the morning.

I considered that, but it’s not the one. I realized it connects to a separate length of wire that also connects to the engine at two points around the oil filter.

Happy to have that figured out. Thanks for the help everyone. Unfortunately I messed up something when connecting the wiring for the glow plugs. I found my mistake but lost a fusible link in the process.

 

[roscoFJ73]

Both my 75 series had that plug. It would be in the Body Chassis manual in the schematics

 

[GTSSportCoupe]

I considered that, but it’s not the one. I realized it connects to a separate length of wire that also connects to the engine at two points around the oil filter.

Happy to have that figured out. Thanks for the help everyone. Unfortunately I messed up something when connecting the wiring for the glow plugs. I found my mistake but lost a fusible link in the process.

Glad you'd sorted it ok. I'd look at mine but couldn't find that connector.

Heh, I've blown the same fusible link before. Made a nice little puff of smoke. I got the spacers wrong at the stud on the intake manifold soon after I'd bought my truck. Grounded out the glow circuit there. Ended up just replacing the fusible link with some wire to get me by until I found an appropriate fuse. Never got around to it, haha.

 

[Cascadia]

Glad you'd sorted it ok. I'd look at mine but couldn't find that connector.

Heh, I've blown the same fusible link before. Made a nice little puff of smoke. I got the spacers wrong at the stud on the intake manifold soon after I'd bought my truck. Grounded out the glow circuit there. Ended up just replacing the fusible link with some wire to get me by until I found an appropriate fuse. Never got around to it, haha.

That’s exactly what happened to me. I’m probably going to cheat and use a wire until I figure out the part number and get it ordered. By the looks of it, it’s been replaced before.

 

[coldtaco]

NAPA has generic fuseable links in different ratings

 

[roscoFJ73]

I’m probably going to cheat and use a wire until I figure out the part number

I took the remnants of the wire to a parts shop, found the appropriate size and made my own with enough wire to make a few more for $5. And as Taco says you can get quite a few more types of fuses and breaker at parts shops

 

[Cascadia]

I took the remnants of the wire to a parts shop, found the appropriate size and made my own with enough wire to make a few more for $5. And as Taco says you can get quite a few more types of fuses and breaker at parts shops

Good idea, I’ll likely do that. I’m out working on it now, fusible link issue is solved but it won’t start. Don’t think I’m getting fuel. Beyond frustrating.

 

[GTSSportCoupe]

Good idea, I’ll likely do that. I’m out working on it now, fusible link issue is solved but it won’t start. Don’t think I’m getting fuel. Beyond frustrating.

Pump the fuel primer for a long time - until it gets hard. Takes quite a bit of cranking too. Make sure to rest the starter between cranking. Also, floor the accelerator when you're cranking to get maximum fuel moving. Just be patient.

 

[roscoFJ73]

Pump the fuel primer for a long time - until it gets hard. Takes quite a bit of cranking too. Make sure to rest the starter between cranking. Also, floor the accelerator when you're cranking to get maximum fuel moving. Just be patient.

How do these pumps shut the fuel off? Just wondering if its has a fuel cut solenoid, or something else not being activated

 

[Cascadia]

I’ve done a lot of priming and cranking and I’m definitely getting fuel now, a little smoke out of the exhaust also. Just doesn’t want to catch at all.

 

[GTSSportCoupe]

How do these pumps shut the fuel off? Just wondering if its has a fuel cut solenoid, or something else not being activated

It has a sophisticated fuel cut solenoid called a spill control valve. It meters the fuel for each injection event.

I’ve done a lot of priming and cranking and I’m definitely getting fuel now, a little smoke out of the exhaust also. Just doesn’t want to catch at all.

Did you check your timing belt marks multiple times? You have to crank the motor with a ratchet a few times to make sure things line up perfect.

Also, did any wiring look brittle and damaged when you put it together? Especially the timing sensor out of the pump, the crank sensor, and the spill control valve. Those are the critical items.

You can jumper TE1 to E1 in the little diagnostic box and read out the engine codes by the flashing check engine light. I posted a bunch about this recently, just do a search. If you cant find, let me know and I'll look.

 

[Cascadia]

Did you check your timing belt marks multiple times? You have to crank the motor with a ratchet a few times to make sure things line up perfect.

Also, did any wiring look brittle and damaged when you put it together? Especially the timing sensor out of the pump, the crank sensor, and the spill control valve. Those are the critical items.

You can jumper TE1 to E1 in the little diagnostic box and read out the engine codes by the flashing check engine light. I posted a bunch about this recently, just do a search. If you cant find, let me know and I'll look.

I’m pretty confident in my timing marks being okay. I went through a few full cycles and they remained lined up.

As for my wiring, it all looked pretty decent. I cleaned each connector with contact cleaner and did a thorough visual. No cracks or anything concerning as far as I could see.

I’ll definitely check into the diagnostics stuff you mention.

I’m also going to look further into my glow plug system. I assume I should have power to the connection on the stud on top of the intake manifold, but my test light shows nothing. I mentioned that I fried the fusible link off the battery from grounding, but I also noticed tonight that the 7.5A fuse in the kick panel is not there. The space for it has nothing to hold the fuse (???). I haven’t pulled it apart yet but I’m wondering if the PO bypassed it or put it in line somewhere else. How could I burn out the link if there was no fuse? I also have no reason to suspect my glow plugs weren’t functioning before the engine was pulled. I’ve a bit of reading to do I’d say.

@GTSSportCoupe thanks a lot for your input. It’s much appreciated. I’d probably be having more fun with this if I had a more practical set up. I’m on the north end of the peninsula and the truck is at my buddy’s place past Sooke. Feels like I spend more time driving out there in my (supposed to be) temporary beater.

 

[GTSSportCoupe]

I’m pretty confident in my timing marks being okay. I went through a few full cycles and they remained lined up.

As for my wiring, it all looked pretty decent. I cleaned each connector with contact cleaner and did a thorough visual. No cracks or anything concerning as far as I could see.

I’ll definitely check into the diagnostics stuff you mention.

I’m also going to look further into my glow plug system. I assume I should have power to the connection on the stud on top of the intake manifold, but my test light shows nothing. I mentioned that I fried the fusible link off the battery from grounding, but I also noticed tonight that the 7.5A fuse in the kick panel is not there. The space for it has nothing to hold the fuse (???). I haven’t pulled it apart yet but I’m wondering if the PO bypassed it or put it in line somewhere else. How could I burn out the link if there was no fuse? I also have no reason to suspect my glow plugs weren’t functioning before the engine was pulled. I’ve a bit of reading to do I’d say.

@GTSSportCoupe thanks a lot for your input. It’s much appreciated. I’d probably be having more fun with this if I had a more practical set up. I’m on the north end of the peninsula and the truck is at my buddy’s place past Sooke. Feels like I spend more time driving out there in my (supposed to be) temporary beater.

Any luck with it?

When you turn your key to 'on' and the engine is cold, you should see ~11V at the glow rail for about 7-8 seconds. Then ~6V for another minute or so.

If this is not happening, and you just want to be able to start the vehicle to get it home, you could manually glow it by carefully using a jumper cable. Attached one end of positive cable to glow rail in such a way it can't ground but still makes good contact (Watch out for fuel return rail especially! Don't want to weld to that). Then attached other end of positive cable to battery positive for about 10 seconds. Start immediately. Don't glow longer than 10 seconds at a time as you could damage the glow plugs. This would be easier with a helper. One person to glow and make sure cable is out of way of fan belts etc. And another person to start. Make sure battery is fully charged.

What all did you do on the motor when you had it out?

 

[Cascadia]

Any luck with it?

When you turn your key to 'on' and the engine is cold, you should see ~11V at the glow rail for about 7-8 seconds. Then ~6V for another minute or so.

If this is not happening, and you just want to be able to start the vehicle to get it home, you could manually glow it by carefully using a jumper cable. Attached one end of positive cable to glow rail in such a way it can't ground but still makes good contact (Watch out for fuel return rail especially! Don't want to weld to that). Then attached other end of positive cable to battery positive for about 10 seconds. Start immediately. Don't glow longer than 10 seconds at a time as you could damage the glow plugs. This would be easier with a helper. One person to glow and make sure cable is out of way of fan belts etc. And another person to start. Make sure battery is fully charged.

What all did you do on the motor when you had it out?

Unfortunately I haven’t had any time to get back out to it since my last post. I should be able to get out there mid week I’m hoping.

I’ll definitely give manually glowing it a try. I’ve lots of small 12v batteries and small jumpers from work so I can rig up something easy. It would be great to get it home at least.

I didn’t do too much really. Broke things down enough to get the crank switched. New crank pulley, timing components, water pump. Replaced any gaskets I touched, cleaned up any electrical connections.

 

[GTSSportCoupe]

Unfortunately I haven’t had any time to get back out to it since my last post. I should be able to get out there mid week I’m hoping.

I’ll definitely give manually glowing it a try. I’ve lots of small 12v batteries and small jumpers from work so I can rig up something easy. It would be great to get it home at least.

I didn’t do too much really. Broke things down enough to get the crank switched. New crank pulley, timing components, water pump. Replaced any gaskets I touched, cleaned up any electrical connections.

Glowing requires a fair amount of juice....80A or so for our motors I think? Sometimes smaller batteries have too much internal resistance and have a lot of voltage drop when producing high currents. But if you have a battery intended for 'starting' you should be fine. We have tons of old SLA UPS batteries at work that I use for all sorts of stuff. One thing I found is they're more suited to energy storage than high peak currents.

Probably a pretty obvious thing that you've got covered, but that new crank had a magnet on it for the crank sensor right?

Wish covid wasn't a thing, as I could come out and give you a hand.

What sort of work do you do outta curiousity?