Wiring Harness '78 vs '75 Bay Window

flah5

Hi, all.
We are in the final stages of our first rebuild. ((whew)) Our beloved bus is being handed down to our eldest son who is going into his senior year in high school. We are at the point of no return with the rebuild, and just came to a shocking realization. The wiring harness that we have begun to install belonged to a '75.(long story) Does anyone know if it is going to be able to be used in our '78? Everything seems to fit, but it would explain a few mysteries. We were looking through the manual, and noticed a few differences. Thanks in advance for any knowledge you may bestow upon us. We feel a bit defeated at this point and hope that the stars are in our favor this time. The thought of re-wiring may send my husband over the edge.

busdaddy · Posted: Wed Jul 10, 2013 3:35 pm Post subject:

Welcome, the differences between the 2 are negligable (assuming we are discussing the main harness running to the back) and will interchange fine.
Any pics of your project?
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flah5 · Posted: Wed Jul 10, 2013 3:43 pm Post subject:

Whew.. glad to hear it. Yes, will upload pics soon. We are real excited. We haven't driven it in about 10 yrs. My son was 6 or 7 the last time we ran it. It was so fun to drive. Can't wait! Thanks for your wisdom.

flah5 · Posted: Thu Jul 11, 2013 4:16 am Post subject:

Hi again.. my husband would like me to specify that we are inquiring about the fuel injection harness. I didn't really specify in my first post. thanks again!

flah5 · Posted: Mon Sep 23, 2013 5:24 pm Post subject:

Hello once again. Everything looks good. No juice. We have gone over everything. Husband wants me to ask again about the main wiring harness. We have one from a '75. Our bus us a '78. Are they interchangeable? We are not getting spark to the coil. So frustrating. Quite ready to hang it up. Thank you in advance.

flah5 · Posted: Mon Sep 23, 2013 5:27 pm Post subject:

The harness sits atop the engine.

busdaddy · Posted: Mon Sep 23, 2013 5:49 pm Post subject:

I see you have a pic in your gallery so you already have a camera and know how to post pics, now lets see some of the connections on the engine Wink

_________________
Rust NEVER sleeps and stock never goes out of style.

Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
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Wildthings · Samba Member Joined: March 13, 2005 Posts: 52300

Do you have power to the "+" (#15) side of your coil? That power should come via the wiring harness that runs up to the aux fan hanging from the top of the engine compartment. Kind of funky the way it is done.

germansupplyscott · Posted: Tue Sep 24, 2013 5:16 am Post subject:

flah5 · Posted: Tue Sep 24, 2013 5:24 am Post subject:

No we don't. The coil was tested and is good. We are getting power to and I think from the ignition. The engine will turn over endlessly, but won't fire. The cap and rotor are new, new AFM, new injectors, new engine. timing is set, new spark plugs. He took the double relay off to clean the connections and test it last night. He found the distributor cap was a little loose. Not sure when that happened, but he tightened that up. We haven't tried to start it again since. Hoping it is something simple. He keeps saying he never wanted to be a VW mechanic Wink

, but after this rebuild, he definitely could be.

Will post a picture or two after it is all put back together. Thanks guys!

flah5 · Posted: Tue Sep 24, 2013 5:30 am Post subject:

Hi Scott.. I am pretty sure the AFM connected fine? Not sure how?? At least I didn't hear any cussing about it. Smile

I will definitely ask him about that after work. Possibly the harness was not from the '75 after all? It has been so long since he dismantled both buses. He could have just been mistaken. Thanks for your input, and I apologize for our ignorance. We do appreciate all that we are being taught.

germansupplyscott · Posted: Tue Sep 24, 2013 6:27 am Post subject:

in this kind of situation it's usually something simple. you're replaced/repaired many parts so the chances of something gone awry are great, but it will come good.
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flah5 · Posted: Tue Sep 24, 2013 6:38 am Post subject:

Fingers are crossed For something simple. Thanks. Will post again after i talk to him later. Have a great day!

Wildthings · Samba Member Joined: March 13, 2005 Posts: 52300

The power from the #15 terminal on the coil to trigger the double relay is pretty funky. Do you have the black wire with the inline fuse in it hooked up to the "+" (#15) side of your coil?

flah5 · Posted: Tue Sep 24, 2013 11:36 am Post subject:

Thank you Wildthings for your suggestions. Will Check then!

canadianveedub · Posted: Tue Sep 24, 2013 12:03 pm Post subject:

I highly suggest finding an L-Jet manual (they are available to download for free). There is a specific l-jet troubleshooting guide that will take you through all of the steps.
Second, are you SURE that you are not getting spark? I always carry an inline ignition tester to check if there is spark coming from the ignition coil. Everything else can check out, but you may still have no spark. The l-jet ECU is dependant on the coil sending spark to trigger an injection event. I had the grounding signal at the coil from the ignition, and 12 volts to termianl 15, but terminal 15 was loose on the coil causing no spark, causing no injection etc.

Once you have spark, make sure that you have the ECU connected to terminal 1 of the coil and then check for injector operation with a test light while cranking. If you have spark and injectors are firing, but still no start, you probably have a fuel supply issue. The double relay uses a signal from the airflow meter to activate the fuel pump. If you deflect the air meter by hand with ignition on, does the feul pump turn on? It should.

I highly recommend using an l-jet guide. It will walk you through the steps methodically and save you a lot of time. Here is a link to the one I used.

http://www.google.ca/url?sa=t&rct=j&q=&...4380,d.b2I

flah5 · Posted: Tue Sep 24, 2013 12:39 pm Post subject:

Thank you! That is very helpful!

flah5 · Posted: Tue Sep 24, 2013 12:49 pm Post subject:

Scott.. the harness must be newer than he thought. It all hooked up fine.

Wildthings.. the black wire with the inline is connected to the + side. Also, we are connected (coil to the wiring harness) via the aux fan on the top of the engine compartment.

He said that the connectors in the double relay were green, so he cleaned them proper.

Will use the guide.. THank you!... and trouble shoot some more.

I will also try and get some more specific details as to what was tested, what was getting power and what wasn't.

It is so exciting and nerve wracking at the same time!!

THank you all for your time!

flah5 · Posted: Wed Sep 25, 2013 3:21 am Post subject:

Anyone feel like a road trip? Haha! Husband said he is done. We need a mechanic.

flah5 · Posted: Thu Sep 26, 2013 12:32 pm Post subject: We have power to the coil!!!!

OKAY!! We have power to the coil! Holy moly! It was the wire from the aux. fan. Doy. Embarassed

We held our breath to try and fire it up.. it turned over for about 10 seconds and then nothing. It won't even turn over anymore. Gah! Now what? Starter maybe? I will take some pics later and post them if you all don't mind. Thanks again for all your help. One step forward, two steps back.


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