RE: 95 EX Vtec. Code 4 Please Help

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RE: 95 EX Vtec. Code 4 Please Help - 6/21/2008 9:40:22 AM    twinturboyan   Posts: 10 Joined: 4/26/2008 Status: offline Ok guys I am getting some progress here. I checked at the distributor and it was 840. Then I checked @ the 14 wire plug by the fuse box and it was 840. Then I checked @ the ECU and it was lower @ 640. There are three plugs on the ecu and I pulled the middle one out (16 wire) and seen the blue/yellow and blue/green wire then  tested it. What do you guys think that should bbe the cause the wire between ECU and 14 wire plug? There was another unit there next to the ecu it had 2 plugs on it which the the same blu/yel & blu/gre wires on on it. What is that unit? Thanks so much guys for all the help. _____________________________ 95 Accord, Auto, 4 cyl. vtec, (in reply to TexasHonda) Post #: 16

RE: 95 EX Vtec. Code 4 Please Help - 6/21/2008 10:11:15 AM    PAhonda   Posts: 1348 Joined: 9/22/2006 Status: online The second unit is most likely the trans. control unit (TCU).  The 640 ohm reading is outside of the range in the 95 shop manual (700 - 1300 ohms).  There must be a short in the wire.  There is one last electrical test in the shop manual.  Test the blu/grn wire to body ground for continuity at the ECU connector.  That circuit should be open.  If that wire is gounded, then you need to repair that wire.  The wire feeds into the cabin through a grommet under the engine bay fuse box as part of the main wire harness from the 14 pin connector.  I don''t know the best way to feed the new wire in, so someone will have to give you more detailed instructions. Good Luck. _____________________________ 1995 Accord EX MT (in reply to twinturboyan) Post #: 17

RE: 95 EX Vtec. Code 4 Please Help - 6/21/2008 10:21:24 AM    TexasHonda   Posts: 1507 Joined: 2/18/2007 Status: offline I would be sure the VOM was zero''d. A change of 200 ohms is suspicious and difficult to account for. It could indicate a cross-connection to another wire. Try to isolate the wire at fault as follows. W/ the connector to ECU disconnected, separately ground the two wires (blu/grn & blu/yel) at the 14 wire plug at the fuse box. Now measure resistance from ground to each socket at the ECU connector. They should show very close to zero resistance. A wiring fault likely would be an open circuit on one wire. A short to another wire would probably show as decreased resistance, but not a dead short. Similarly, remove the jumpers to ground at the fuse box and check the ECU connector pins resistance to ground. Both wires should show open. Any reduced resistance would indicate a wiring fault (short to ground or another wire) in the harness. Above should allow you to isolate which wire is causing the problem. Examine the connections (both ends) very closely for and damaged male pins or female sockets. good luck _____________________________ See you down the ROW 1994 Accord EX (in reply to twinturboyan) Post #: 18

RE: 95 EX Vtec. Code 4 Please Help - 6/21/2008 2:17:17 PM    twinturboyan   Posts: 10 Joined: 4/26/2008 Status: offline Ok guys I made a mistake. My meter was acting up and I got wrong measurment @ the ECU. So here is the measurements.  862 @ Distributor, 862 @ 14 plug connector by the fuse box, & 861/862 @ the ECU connector. So it all checked out. I am going to try to do that continuity to groung but I don''t yet understand how that works. This is getting really technical for me. I was thinking about giving up but I will continue because I am in too deep. No point of quiting now. The shop manual I downloaded from Hondahookup. What page is this information on about continuity to ground? Yan _____________________________ 95 Accord, Auto, 4 cyl. vtec, (in reply to TexasHonda) Post #: 19

RE: 95 EX Vtec. Code 4 Please Help - 6/21/2008 2:19:06 PM    twinturboyan   Posts: 10 Joined: 4/26/2008 Status: offline Could the ECU/ECM be bad?  _____________________________ 95 Accord, Auto, 4 cyl. vtec, (in reply to twinturboyan) Post #: 20

RE: 95 EX Vtec. Code 4 Please Help - 6/21/2008 4:54:18 PM    PAhonda   Posts: 1348 Joined: 9/22/2006 Status: online TexasHonda basically gave you directions to determine which wire is at fault.  He was trying to help you determine which wire to repair open wire on page 11-43.  Since your tests came back within the proper range, you do not have to do this.  He basically wanted you to unplug the 14-pin connector and hook a wire up to one of the two pins on the ECU side of the connector and connect the other end of that wire to the engine block (ground).  Then he wanted you to to measure the resistance at the ECU plug to body ground and report the readings.  The reading should have been zero (or close) for both wires.  A different reading would have indicated a bad wire. You are basically at the end of the diagnostic tree.  There is one last test on that page.  You probe the B15 pin at the ECU connector (blu/grn wire) to ground and check if is a continous circuit.  Most digital volt meters have a setting for continuity where the meter beeps when you touch the probes together (closed circuit).  Put the red tip in the ECU connector at blu/grn wire and touch the black probe tip to a bolt that screws into something metal (or touch threaded hole for the ECU cover).  That should cause the volt meter to beep, ie a closed circuit.  That blu/grn wire at the ECU connector should be a closed circuit. If you do not have this continuity function on the meter, use the resistance setting.  A resistance of zero (or close to zero) would also mean a closed circuit.  < Message edited by PAhonda -- 6/21/2008 5:04:22 PM > _____________________________ 1995 Accord EX MT (in reply to twinturboyan) Post #: 21

RE: 95 EX Vtec. Code 4 Please Help - 6/22/2008 6:34:39 AM    TexasHonda   Posts: 1507 Joined: 2/18/2007 Status: offline I''ve re-read this entire thread, and suggest swapping a used ECU to your car to check. It could be a fault in the ECU circuit board. That is all that is left. ECU''s are very good and frankly this is a long shot, however considering all your effort, I don''t think you should stop now. Check car-part.com for a replacement ECU near you. You should be able to find a unit for <$100 easily, perhaps < $50. Hope you got a good deal on the car since you''ve had a lot of bad luck. good luck _____________________________ See you down the ROW 1994 Accord EX (in reply to PAhonda) Post #: 22

RE: 95 EX Vtec. Code 4 Please Help - 6/22/2008 8:16:07 AM    twinturboyan   Posts: 10 Joined: 4/26/2008 Status: offline Yeah that is my next plan. I seen a lot of accords at the junk yard here in Toledo, OH. But most of them are LX model or stick shift. Can I use those ECU''s or does the car have to be and EX? I bought the car for $500 invested $700 in  it already and I am not giving up now. I will keep everyone posted on what happens. This is my summer project. lol _____________________________ 95 Accord, Auto, 4 cyl. vtec, (in reply to TexasHonda) Post #: 23

RE: 95 EX Vtec. Code 4 Please Help - 6/22/2008 8:26:32 AM    TexasHonda   Posts: 1507 Joined: 2/18/2007 Status: offline The site car-part.com will tell which cars are donors to your cars so check it out. I don''t know for sure, but I''ve found their cross-reference feature to be very handy. I think ECU replacement does have to be from an EX, because the LX does not have Vtec and Vtec is actuated based on a pre-mapped schedule embedded in firmware of ECU. good luck _____________________________ See you down the ROW 1994 Accord EX (in reply to twinturboyan) Post #: 24

RE: 95 EX Vtec. Code 4 Please Help - 6/23/2008 7:13:17 AM    JimBlake   Posts: 3272 Joined: 5/31/2006 Status: online I read the stuff about continuity to ground... The wires should NOT have continuity to ground.  So if you use the RESISTANCE setting on the meter it should NOT read zero.  Zero resistance is a GOOD connection to ground, a short circuit. You want the meter to read overload or infinite resistance.  Whatever it displays when you simply hold the meter leads & dont touch them to anything. _____________________________ '03 Accord & '07 Civic '01 Saab 9³ & '05 9²x (in reply to TexasHonda) Post #: 25

RE: 95 EX Vtec. Code 4 Please Help - 6/23/2008 2:35:00 PM    twinturboyan   Posts: 10 Joined: 4/26/2008 Status: offline OK guys we did it once again. This problem is SOLVED. I bought a ECU from junk yard for $40. They give me good deal since I bought so many parts from them already. Plugged it in. CEL is gone revs perfect. VTEC kicks in. Pretty fast car I would say. My friend opened the ECU and said it had a bad resistor. This is rear for Hondas but who knew. Thanks guys. All of you are great.    The dealer told me all I needed was a "tune up" using OEM parts. I paid $100 for that diag. But it needed a new engine and ECU. I got to get my money back. lol  1 luv Yan _____________________________ 95 Accord, Auto, 4 cyl. vtec, (in reply to JimBlake) Post #: 26

RE: 95 EX Vtec. Code 4 Please Help - 6/23/2008 9:55:49 PM    JimBlake   Posts: 3272 Joined: 5/31/2006 Status: online Cool, glad its fixed.  ECUs are pretty robust, so all the measuring was to rule out bad wiring which is actually more likely than a bad ECU. _____________________________ '03 Accord & '07 Civic '01 Saab 9³ & '05 9²x (in reply to twinturboyan) Post #: 27

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