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Discussion Starter #1 (Edited)
Hello, I'm trying to replace a jumper harness back to oem obd1 plugs but the colors don't always match up. For example A1 isn't brown it's yellow with red stripes. There are also a bunch of extra wires and this extra connector that has been spliced into the oem wiring and A26 leads to one brown/black wire and one solid brown wire that leads into that connector and then to the bundle in the picture. I'm also having a strange issue with the blinker fuse. With the fuse in and key on the fuel pump doesn't stop priming and just keeps running. If I crank the key after the prime is supposed to finish the car has problems starting but will eventually start and run. If i crank the key right away the car will start and stay running and drive semi decent. If I take the blinker fuse out the pump will prime like normal and the car will also start, but run like crap and using the blinkers or hazards makes the lights dim in sync with them. I looked up pinouts and read a few obd0-obd1 install instructions but I couldn't figure out which wire the blinker was. Or what to do about the spliced stuff. Any help would be appreciated. The gas gauge and temp gauge also don't work and I'm wondering if this would have anything to do with that as well. Am I physically going to have to use a meter and check every single wire on the car? My time is limited so there has to be an easier way.

The car is an 89 civic dx hatchback with a 95 b7 and z6 head. Chipped ecu.


 

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Brokedick Millionaire
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every single wire, one at a time. 25 billable hours between two people. $2000.

Likely injectors are hanging open and you are flooding the cylinders or intake manifold. Good way to hydro lock the motor and bend a rod.

I can fix the problem for $3, gallon of diesel and a match, problem solved.
 

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Discussion Starter #3 (Edited)
Holy geez. And you think the issue is likely in that rats nest of wiring or elsewhere in the harness? The blinking in sync was always an issue until I changed the fuse, then that problem stopped but the pump constantly running started. Unless I remove the fuse (which the blinkers still work, what?) and then the dimming in sync comes back.
 

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Man what a mess. For the blinker issue there’s probably a problem somewhere else in the harness but could be in the main relay wiring. Hard to say for sure as odd things start to happen with that kinda of mess. A missing ground could cause odd issue,a power going some where it shouldn’t causes issue.
 

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Brokedick Millionaire
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The EF HB I helped rewire was a DX converted to MPFI with a DOHC ZC swap. First by the kid himself, then another shop. It was towed into Tim's and he spent no telling how many hours and Smirnoff Ice's trying to get it right. Then Ryan (nitroedHX) and I started chasing the wiring using a multimeter and long test leads to trace the wiring from ECU to sensor. After about 3-4 hours of frustration I took a pair of side cutters and CUT the three bundles at the ECU and we traced and spliced EVERY circuit one by one for another 8 hours.

Tim laughed and bet us it wouldn't start up on the first try. Well it did sorta start and was running rough. I knew from others ZC installs to swap the wires on the cam sensor....and said a short prayer to the Honda Gods.

Fired right up, 1700 rpm idle all nice and smooth. BTW it was in December, also the night I met Jen, she was only 15 then.

I still have nightmares about that wiring mess!
 

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Discussion Starter #7
every single wire, one at a time. 25 billable hours between two people. $2000.

Likely injectors are hanging open and you are flooding the cylinders or intake manifold. Good way to hydro lock the motor and bend a rod.

I can fix the problem for $3, gallon of diesel and a match, problem solved.
Yeah, considering I'm not the one who screwed it up in the first place, you can understand me seeking help elsewhere.
 

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Discussion Starter #8
I figured it would be easier to test if I swapped out the plugs first. There were a few pins filled that don't show anything on the pinouts that I'll have to trace. The o2 wires are 4 different colors. 2 before the plug, then 2 after. I was left over with one that starts red, then goes to black and white, then straight black, then brown and yellow. There was also some shielding on the car side harness that doesn't go anywhere. Probably not much better than before but it's a start. Been at this for a few hours and it's time to sleep. I'll continue as I have more time, can't really try to start it anyway until I get a new downpipe.



 

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Looks better all ready. Since this is a conversion there are added wires like the O2 sensor and most likely distributor and a few others I can’t remember at the moment as the chassis didn’t come with them from factory.
 

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Discussion Starter #10
Round 2. First thing I disconnect the main relay and the ecu. Put the key to ON and the fuel pump runs. I attempt to check for continuity in the ecu plugs and at first I'm getting battery voltage at several pins on all plugs and approx 10.9 at one of them. I check again and the power vanishes. I try to see if I can at least isolate where in the harness the open is and disconnect the passenger shock tower. I turn the key to ON and no fuel pump running. I put the plug back in and it starts running. Take it back out and disconnect the fuel plug under the back seat. I look in the service manual and it says to check the 3 pin connector, but it's not a 3 pin, it's a 4 pin.



I ground the top left pin and check for voltage and I'm getting 12.3ish at the bottom left pin and bottom right pin. I figure maybe I can check the pins at the passenger side shock tower on both ends for any kind of power and nothing. I say fuckit and this happened.



While removing the harness I notice that the thermostat connector wasn't connected at all. Is that why the temp gauge in the cluster isn't working?




The harness was already too short and it was routed between 2 looped coolant lines so I'm assuming as the motor flexes under boost (it does, herky jerky to the max, no front mount since I have the sparktec hydro to cable conversion, and only 3 innovatative 60-65a trans engine and rear mount) so I figure now is a good time to remove all the tape and loom and inspect for breaks or missing connections. I found a couple crimps that look like they were connected to something, and the reverse switch wires are completely trashed.




I did as much as I could and this is where I'm at right now.



I will continue updating this post as I go. I didn't really see any breaks in the wiring so I think I might have to pull it ALL out. If i do does that mean I have to remove the dash to get the rest of it out? Maybe I'm going about this the hard way but hopefully not.
 

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BATSLOMAN GIVES NO FUCKS.
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the thermostat is just a ground. it will cause a lot of wonky things when not tight/clean
 

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That 2 wire round gray plug and the 2 wires you found by the thermostat housing are for fan switch most likely. Obd0 has the fan switch on the back of the block where’s the obd1 motor has it in the thermostat housing. It’s just a ground switch triggered by temperature to turn fan on and off.

The reverse light switch is also different from obd0 to obd1

To get the whole harness out of the car the dash will need to come out along with the heater box. At this time I don’t think it’s a good idea to remove the harness from the car as you need it hooked up to determine what is causing your issues and that’s pretty hard to do with it out the car.
 

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Discussion Starter #14
What is that shielding and where does it go? It's routed with the wires from the bigger dizzy plug. There's also some routed with a big orange wire on the car side.

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It looks like they took that from an obd1 harness to convert the obd0 harness. That little piece of silver bare wire goes to ground but only one side of the shielding wire.
 

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Discussion Starter #16
Sweet, it is grounded on one side. Here's everything after I extended the connectors that needed it and re taped and loomed it up.



I got it all reinstalled. I have to make sure the o2 wires are routed right and then it's back to trying to find this blinker/fuel pump issue. I noticed that with the main relay and ecu disconnected and key on it still does it.
 

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Looks good. The blinker/fuel pump issue could be a bad ground some where. There’s ground blocks on both sides of the inner fender,those have the grounds in it for headlights,blinkers,parking lights and fan. Make sure there’s no breaks and there clean.
 

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Discussion Starter #18
Ok, so not sure if I'm even doing this right. First off there wasn't a 3 pin on the fuel access port it 4 pin. The bottom 2 wires go to the pump and the top 2 wires are the sending unit. I connected the negative on my meter to where the ground is supposed to go on the car side of the plug and went pin by pin on the ecu plugs and this is what i found

A4 - 7.3v
A23 - 9.3v
A24 - 9.3v
A26 - 9.3V
B5 - 3.5V and kicks on the fan
D1 - 12.3 v
D6 - 9.3v

With the negative test lead on the power wire of the 4 pin plug

A4 - 3.5v
A23- 4.2v
A26 - 4.2v
B2 - 4.2v
B5 - 3.6v and runs fan
D1 - 8.4v
D2 - 4v
D6 - 4.2v

Now with the test lead on the bottom pin of the blinker fuse at the fuse box

D1 - 8.3v
D2 - -7.2v

With the test lead on the top

A4 - -10v
A23 - -12v
A24 - -12v
A26 - -12v
B2 - -12v
D1 - 85v???
D2 - -12v
D6 - -12v
D9 - -11.5v

What now?
 

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Hey! I just came upon this post. Let me review everything that you've posted and see what if I can help at all. I saw that its a 89 DX and has a "95 b7 and z6 head". Sorry if Im not up to date with the current lingo but what vehicle does that block come out of? If I remember correctly, the z6 head is from a 92-95 si, correct?

I agree with 2JZDreamin that it could be a bad ground. If you have a bad ground then the voltage that is supposed to be going to ground (and then the battery) is instead "back-feeding" through other components. If there is continuity, electricity will find it.

What also could be causing your strange issues is a short to power in the wiring. You could have a "hot on run" wire that is shorted to a splice somewhere in the wiring. The fact that you are getting such strange voltages all over the place means that the voltage is going to a bunch of places at once. The only way that your voltage should read anything less than 12v is if its going through some kind of resistance. That could be a poor ground, a corroded wire, or the voltage is going through some component that is using it.

When Im at work tomorrow I will look at some of the wiring diagrams for your vehicle and see if I can figure anything out from there.
 

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A23,24 and 26 are grounds to thermostat housing and shouldn’t be showing voltage with your meter hooked up to ground. Was the ecu plugged in when you tested it?
 
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