Honda Civic / Del Sol (1992 - 2000) EG/EH/EJ/EK/EM1 Discussion

Bringing life back to an abused 92 CDM VX

 
Old 06-12-2019, 05:38 AM
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Default Re: Bringing life back to an abused 92 CDM VX

Originally Posted by tony_2018 View Post
Which way do you have the line on the diode face, and what are you using the diodes for again?
Sorry, forgot to answer this. The line side of the diodes is facing the peripheral wires (door and trunk wires) the non line side was facing the alarm.

Using the diodes to isolate each line attached to a single negative input on the alarm. This is supposed to prevent the trunk light from lighting up when either door opens up or if there is a door light, prevents the open door light from lighting up when the trunk is opened.
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Old 06-12-2019, 06:17 AM
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Default Re: Bringing life back to an abused 92 CDM VX

GRN/RED from the dome light passes through the ICU where it turns into GRN/BLU (or whatever colour is at the driver door dome light switch). The ICU pass-through is required for the key-in & door-open feature.

My first guess is the alarm is incorrectly wired, and is grounding the GRN/RED when it's not supposed to. Possibly a diode issue. I've seen it where the dome ground is wired to the trunk light ground but these aren't diode isolated so when the door is opened the trunk light goes on. This will correctly set off the alarm when a door or the trunk is opened and the alarm is set but yeah it's wrong.

The way GRN/RED runs is something like this: From the dome light, down the A-pillar, to a 2-pin connector kinda sandwiched between the left side of the dashboard and the body (C701/C420). Above or nearby the hole that the door wires exit through to the door. GRN/RED splits after this connector to go to the ICU and to the passenger side dome switch. It runs along rear harness under the carpet, between the driver's seat and the door, to about behind the lower seat belt mounting point, then turns to run behind the rear passenger footwell carpet over to the switch. The other GRN/RED at the split enters the ICU and exits again as GRN/BLU then follows the same harness path but just to the driver's side door switch.

Tapping in to the GRN/RED anywhere along its length will provide the necessary trigger. However, it must be diode-isolated from the trunk-open ground. These are usually tied in to the same "door-open" trigger on the alarm brain. If this is the problem, of course. Even if it's not, my sense is still that GRN/RED is grounded prior to the door switch.

Last edited by deschlong; 06-12-2019 at 04:43 PM.
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Old 06-12-2019, 09:02 AM
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Default Re: Bringing life back to an abused 92 CDM VX

Pretty sure the trunk is separate but it has been a while.
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Old 06-12-2019, 09:09 AM
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Default Re: Bringing life back to an abused 92 CDM VX

Originally Posted by tony_2018 View Post
Pretty sure the trunk is separate but it has been a while.
It definitely is, but when *some* people wire the alarm, they tie the two together without diodes to trigger the alarm (for the door-open sensor), and in the process fudge up the existing car wiring.

TomCat should see if the dome light works properly when the trunk is popped open.
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Old 06-12-2019, 09:12 AM
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Default Re: Bringing life back to an abused 92 CDM VX

Yeah I usually look for the wiring that goes to the lighting in the trunk and connect to the ground there and BOOM trunk trigger, so its separate. Older alarms only had a few trigger wires so for them to wire the trunk, door and hood pins together DOES require a diode. Newer alarms have separate triggers for each now so a diode isn't needed,
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Old 06-12-2019, 09:16 AM
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Default Re: Bringing life back to an abused 92 CDM VX

Good to know. When I installed one around 2012 it didn't have separate lines for these. I'm guessing TomCat is dealing with an older alarm that might have this same issue.
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Old 06-12-2019, 09:18 AM
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Default Re: Bringing life back to an abused 92 CDM VX

So the diodes have to be set the correct way.
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Old 06-12-2019, 06:00 PM
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Default Re: Bringing life back to an abused 92 CDM VX

Thanks guys.

As far as I can tell, the drivers door is not grounded so it's after the ICU from the drivers door switch. I haven't tested the passenger side switch wire to see if it is showing ground yet but will.

I'm using the solid green wire in the cluster harness for my trunk trigger. And yes, it's an older alarm with 1 negative trigger wire and 1 instant negative trigger wire. I am using diodes to keep the door and trunk triggers isolated. When I took the diodes out and just connected the door to the alarm neg trigger wire, didn't work as it's grounded at all times at the moment as mentioned before, but worked just fine when I tied it to the green trunk wire (hatch glass technically). I think if it was tied together, the green wire would also be constantly grounded and the trunk light would always be on.

I think I have a short somewhere between the dome light and the ICU on the green/red door wire. I thought I had found the C701/C420 connector but looks like I missed it as you mention it's a 2 pin connector with the white/blue and the green/red wire that then works to the ICU in the main harness.

I'm hoping I don't have to rip out the dash or pull the sound deadening material to get to the main harness running under the carpet from driver to passenger side.

Thank you again deschlong, that was very helpful information you posted up above! Highly appreciated! I was studying the FSM and ETM but it's not the easiest to piece together for somethings, like the dome light.

I'll post up any updates if I find anything not already mentioned. Cheers!
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Old 06-12-2019, 08:05 PM
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Okay, I tested all the wires to ground and could not get continuity. Plugged everything back in and together, still could not get continuity to ground. So I'm confident there is not a short to ground anywhere.

I then started fiddling with the drivers door switch and watching the dome light (has LED bulb). When I was checking resistance from my green/red wire to ground I was getting negative resistance so I switched to DC volts and found when door is closed, I'm reading 700 millivolts on my green/red wire with bulb in. Door open I read 7+ volts with the bulb in. When I turn dome light to off or I pull the bulb out. I cannot get continuity to ground regardless of door open or closed on the green/red wire.

I think the ICU might be the problem. I checked the part number and it's the correct ICU but has been replaced with a new part number so is likely the original. It seems the ICU is letting voltage bleed through to the ground wire (green/red) and isn't providing ground to the green/red unless the circuit is completed with a bulb installed on the dome light. If the light is switched to off, the green/red never is seen as ground and that doesn't seem right as that wire should work as a negative trigger for the alarm.

Please let me know if you notice any flaws in my thoughts or if I am mistaken on any part. I am wondering if the low resistance of the LED dome light bulb caused the ICU to eventually fail. I will see about grabbing a regular bulb when I grab an ICU from the salvage yard this weekend.
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Old 06-12-2019, 08:27 PM
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Default Re: Bringing life back to an abused 92 CDM VX

LED bulb might be throwing you off. I think i read about this before
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Old 06-12-2019, 09:20 PM
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Default Re: Bringing life back to an abused 92 CDM VX

Originally Posted by tony_2018 View Post
LED bulb might be throwing you off. I think i read about this before
Okay thanks, I will try that first, then if not replace ICU.
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Old 06-13-2019, 05:59 AM
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Default Re: Bringing life back to an abused 92 CDM VX

Don't you own another 5G Civic? Try temporarily swapping the ICU. If not, jumper the GRN/RED and GRN/BLU on the ICU connector when it's unplugged. This bypasses the ICU and the driver's dome light switch will operate like the passenger one does. This test will tell you if the ICU is indeed the problem if the dome light functions properly without it.

Also, have you disconnected the alarm connections to the dome? To eliminate the variable.

If you do get another ICU, note that you have a number of options that give you additional features. Door-open from a 6G Civic or 3G Intégra, door-open + rear int wiper from a 1G CR-V.

Other tests if the ICU is not the problem:
  1. Unplug the connector at the ICU.
  2. Check for continuity between the dome GRN/RED and ICU GRN/RED at the connector. Post result.
  3. Check for continuity between the dome and GRN/RED at the passenger side door switch GRN/RED. Post result.
  4. Check for continuity between ICU GRN/RED GRN/BLU at the connector and at the driver's side door switch GRN/BLU. Post result.

Last edited by deschlong; 06-13-2019 at 11:12 PM. Reason: typo
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Old 06-13-2019, 11:29 AM
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Default Re: Bringing life back to an abused 92 CDM VX

wtf HE DOES
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Old 06-13-2019, 06:21 PM
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Default Re: Bringing life back to an abused 92 CDM VX

Originally Posted by deschlong View Post
Don't you own another 5G Civic? Try temporarily swapping the ICU. If not, jumper the GRN/RED and GRN/BLU on the ICU connector when it's unplugged. This bypasses the ICU and the driver's dome light switch will operate like the passenger one does. This test will tell you if the ICU is indeed the problem if the dome light functions properly without it.

Also, have you disconnected the alarm connections to the dome? To eliminate the variable.

If you do get another ICU, note that you have a number of options that give you additional features. Door-open from a 6G Civic or 3G Intégra, door-open + rear int wiper from a 1G CR-V.

Other tests if the ICU is not the problem:
  1. Unplug the connector at the ICU.
  2. Check for continuity between the dome GRN/RED and ICU GRN/RED at the connector. Post result.
  3. Check for continuity between the dome and GRN/RED at the passenger side door switch GRN/RED. Post result.
  4. Check for continuity between ICU GRN/RED at the connector at the driver's side door switch GRN/BLU. Post result.
I do but wife has it at work and needs it from time to time.

I was going to run to the store and get a regular bulb to get the LED out of the equation. I also have the later CRV ICU's the one with the internal head light chime but I would need to sit down and re-figure out the couple of repins I figured out on the ignition system. If I recall your write up the crv you had an external chime and was only from the 98, I think mine are from 99+

And yes, I unhooked the alarm from the setup and just ran the wire on the trunk to find it works normally and have not moved it back to the dome while I isolate the door wires and ICU stuff.

I will do the above tests and report back as well as get the LED bulb out of the dome light.

On #4, the green/red is one pin on the ICU connector and the green/blue is another. I'm assuming you want to see no continuity and this test is with the connector unplugged from the ICU?
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Old 06-13-2019, 08:01 PM
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Default Re: Bringing life back to an abused 92 CDM VX

Okay, I don't have access to another 5th get ICU at the moment.

I have continuity from ICU green /red to pillar green/red, also ICU to dome green/red and ICU to passenger green/red. I also have continuity from dome to passenger green/red. I do not have continuity from green/blue to any green/red regardless if connector is in ICU or not.

And dome light is operating normally.

With dome light set for door activate, I read 12 volts from pillar green/red to ground when door closed, 910Milli volt with door open. This seems normal.

Where it does not seem normal is put dome light to off. Dome no longer has any path to ground. Continuity to ground at pillar green/red is not there regardless if door is open or closed. There is a flash of low resistance (120ohm) for a millisecond when door opens, then goes back infinite resistance.

I was under the impression there should be ground present as the alarm is not supposed to be reliant on dome light switch settings.....
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Old 06-13-2019, 08:04 PM
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Default Re: Bringing life back to an abused 92 CDM VX

That is true, the trigger should still go off even if the dome light is off. Once the trigger wire receives a ground signal it sounds the alarm. I might have to check my wires to see whats
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Old 06-13-2019, 08:12 PM
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Default Re: Bringing life back to an abused 92 CDM VX

Originally Posted by tony_2018 View Post
That is true, the trigger should still go off even if the dome light is off. Once the trigger wire receives a ground signal it sounds the alarm. I might have to check my wires to see whats
I know the trigger wire works as the green trunk wire receives ground and sets off alarm regardless if key is in ignition or car is on etc.

This is what caused me to think the ICU is faulty. That and that even with door closed on door activated dome the led had slight illumination. So some power is slipping through when door is closed and ICU is not receiving ground trigger from door.
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Old 06-13-2019, 11:10 PM
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Default Re: Bringing life back to an abused 92 CDM VX

Oops #4 had a typo, I meant continuity between GRN/BLU at door and GRN/BLU at ICU connector. I'll fix it.

So you're saying the dome works properly if you jumper GRN/RED and GRN/BLU at the ICU connector.

I'm partial to agreeing with you on the ICU diagnosis. There's a diode in there that's rooted. Now's the time to install the CRV ICU, then.
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Old 06-14-2019, 05:16 AM
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Default Re: Bringing life back to an abused 92 CDM VX

Originally Posted by deschlong View Post
Oops #4 had a typo, I meant continuity between GRN/BLU at door and GRN/BLU at ICU connector. I'll fix it.

So you're saying the dome works properly if you jumper GRN/RED and GRN/BLU at the ICU connector.

I'm partial to agreeing with you on the ICU diagnosis. There's a diode in there that's rooted. Now's the time to install the CRV ICU, then.
I forgot to do the jumper at the ICU connector. I'll do that after work tonight. I did check and do have continuity of the green/blue from door to ICU connector. I did check that.

I wish I knew what I did with my CRV notes. I'll have to print off the fsm sheets again. Things got lost in the move 2 years ago.

Addendum
-----------------------------------------
I didn't do anything with the car tonight. Long week and pretty sore. I did print off a couple of the CRV fsm pages to realize, deschlong's old crv ICU write up was using the unique 97 CRV ICU and when I was grabbing them I had the more prevalent 98-00's available. Now sitting down looking at the connectors on paper, I remember about the deciphering I was doing. 10 pin to 15 pin conversion. Also realized I need to print off the CRV ICU schematic to piece together the wires.

I think I might grab another 95 civic ICU at the yard Sunday unless I get off early tomorrow and can do it then. I can then quickly isolate if the ICU is the bad link in the equation and fall back to that if I'm not able to re-decipher the pin outs and wire routes in a timely fashion. I definitely agree, right now is the time to do it though as all the under dash wiring is openly exposed right now as is the column wiring. This weekend is crunch time and I'm work OT so we'll see how it goes.

And don't worry, I didn't forget, I still need to do the short the green/blue to the green/red on the ICU connector and see if the dome light operates normally. I'll be doing that before any other ICU goes in, which ever one it will be.

Last edited by TomCat39; 06-14-2019 at 09:08 PM.
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