So I bought a 97 EK hatch and many douche bags have left me a mess that I must now clean up. I have redone everything in this car including the engine, engine grounds, ECU, Engine harness, Etc.... This is the last frontier, Its time to take on the dash harness.

Heres my problems.

1. Hondata s300 randomly locking up while datalogging. (This IS electrical interference) and its not the plugs or wires or dizzy.

2. TPS voltage is intermittent, Correct voltages read when the car is still (.5v Closed), But if any kind of vibrations hit the car (while its not running and the ignition turned forward) the TPS votage jumps .5 to 1 full volt and will not return to normal until the ignition is switched off and back on again. Like if Im measuring the TPS voltage and my buddy sits down in the car my .5v jumps to .8 - 1v and does not come back to where it should be. (See TPS calibration procedure)

3. Another vibration problem, When the subwoofers hit, The gauge cluster RPM & MPH needles go nuts!

4. Hondata also locks when turning the blower motor on, There is no blower motor resistor present AND theres no plug for it...WTF? So the blower motor only works on 3 & 4 and it locks up the s300 while datalogging, everytime.

5. I want to see if you guys know about any of this. It will save me time searching through the book looking for random color codes. I got plugs missing, plugs hanging, plugs jumped to other plugs, Plugs cut, Loose cut wires and so on.

Guys I got a power mirror module and its plugged up and the mirrors are manual...W...T...F

I want to know what this **** is. We'll start here. Look at these pics and see if you can tell me what this stuff is or what it used to be. All these pics are from under the cluster drivers side. Two gray wires with a blue wire jumped to a plug...No idea? And see if you can tell me what that missing plug is right above the ignition module.

1997 Honda Civic DX Hatchback

I have power windows and locks too, Did the DX even come with that ****? This car has been so molested its not even funny.

 

Missing plug around ignition and unknown plug stuffed up in the dash.

 

****ing nightmare. Well the good news is that it seems to be a consistent problem at least which makes diagnosis easier.

Judging by your symptoms, all of the devices having problems all interface with the ECU I/O. I am assuming that the TPS voltage #'s you are referencing are coming from the datacq. It seems like it is a short to batt/ground somewhere in the I/O channels, perhaps on an ADC/DAC supply or ground (analog-digital converters). Do any of the other sensors experience similar problems?

You said that you replaced the engine harness, so it would be nice to rule that out.

Reminds me of a problem in a Mark V GTI race car we built. We had a CAN port spliced in with a connector that was next to the dash bar of the cage. Vibration would cause it to short out and take out the cluster/comms. In this case you don't have CAN, but I would look for a short to ground/battery on the OBD Hi/Lo and the power wires to any device experiencing a symptom.

If all else fails, try unplugging everything possible on the dash (and engine if you must) with the car still able to run, and then drive around bumpin them beats and see if you can ditch any symptoms. Then hopefully it will and will be a process of elimination...

Good luck. I hate fixing other peoples' hack jobs.



[edit]also if you have access to a scope instead of just a multimeter that could be very valuable.
[edit2]regarding missing/unknown plugs. Have you accounted for the following?:

Maint Req Lamp timer box
SRS service plug
OBD port
headlight chime
fog switch/ dimmer pot