pwillikers

I am installing an electronic cruise control (Rostra is the mfg.) in my 1990 CIVIC 1.5 STD. 3DR, Chassis: ED634, Engine: D15B1. I wired the cruise up as follows.
The cruise tach wire goes to the blue wire on the distributor,
the VSS (vehicle speed sensor) wire goes to the yellow/red in the 18 pin connector above the fuse box,
the always on 12v goes to the brake light switch hot lead
the ignition on 12v goes to the hot on the cig lighter
the brake interrupt wire goes to the brake light switch cold lead
and ... the cruise actuator ground ...

I was looking for a good ground for the actuator and had a lapse of my normally incisive judgment (yeah right). I tapped into a black wire on what I believe to be an emissions contraption on the firewall and wired the actuator ground to it. My digi-meter reported it as a good ground (see pic. - it's the black wire from the black and green wire connector)(fyi, the square red plastic junction in the pic is where I ultimately correctly attached to a functional ground which is under a chassis screw).



I started the car up and it ran fine but the LED on the cruise switch didn't light and the cruise didn't function. I rechecked the +12v sources to the cruise, they were fine. Then I made what I believe is my fateful mistake. To check the actuator ground, I ran a lead directly from the negative battery terminal to the junction I had just made between the black wire on the contraption and the ground on the actuator, effectively grounding both to the battery. I turned on the ignition and the cruise LED lit up, hmm original ground must be bad, so I relocated the actuator ground to it's present, chassis grounded, permanent position (ie. the red plastic junction in the pic.). I then tried to start the car which cranked fine but wouldn't start. The "check engine" idiot light on the dash was now lit (idiot light never more appropriately named).

After determining there was no spark, I checked all the fuses (both fuse boxes, under the dash and on the right front fender) - all good, I pulled the carpet back to look at the diagnostic LED in the ECU. I turned on the ignition and the LED didn't light at all. I pulled the connectors from the ECU and found it was getting +12v from two wires (don't recall the wire colors), one which was on all the time the other switched on with the ignition. My Haynes manual states that if the ECU LED doesn't light, and it's got power, the ECU is faulty - so I guess when I grounded the black lead on the emissions contraption and turned on the ignition, I fried the ECU.

Questions:
1. What is the emissions contraption in the picture that I grounded called?
2. What's the likely hood that I damaged the emissions contraption by grounding it such that were I to install a new ECU, it would either not function correctly or I might fry the new ECU? Do I need to replace the contraption? How do I test it's function?
3. Did I really did fry the ECU by grounding the contraption? Does no LED unequivocally indicate a dead ECU? Is there a way to test the ECU?


Modified by pwillikers at 11:00 AM 5/28/2008

jlicrx

1. emissions contraption is the purge cutoff solenoid valve
2. you may have damaged it - car will run fine without it - on most Hondas, black with yellow stripe wires are power and are hot with the ignition switch on - you tapped into hot wire
3. check your fuses - particularly fuse no. 14 in the under dash fuse box - it is power to the main relay for the fuel pump and #1 in the underhood fuse box it is power to the ECU - also check the hazard fuse in the underhood fuse box - usually, when the ECU is bad, the Check engine light will be on and the red LED on the ECU will stay on all of the time

do you have another ECU that you could try?




Modified by jlicrx at 3:47 PM 5/28/2008

hondacivic90zc

like jlicrx said check your fuses and also, if you can, try another main relay to see if somehow you fried that.

pwillikers

Thanks. You were right. I had initially checked the #14 fuse in a dark garage and missed that it was actually blown. Sheesh! A lot of diagnostic work for my being careless not seeing this first.

Anyway, on to the next issue. The cruise still doesn't work. It has a pretty elaborate self diagnostic procedure that indicates that that it's not receiving a VSS. As I posted before, I wired the VSS (vehicle speed sensor) wire from the cruise to the yellow/red in the 18 pin connector above the fuse box, which, according to Rostra tech support, is supposed to be the VSS for this vehicle. From the official Honda manual I downloaded from hondahookup.com, I see the CRX for the same year has a mechanical speedometer cable from the transmission to the speedometer which has a "speed pulser" that outputs on the yellow/red wire. This wire then goes to the ECU. The "speed pulser" outputs four pulses per revolution of the cable.

<U>Questions:</U>
How do I check the function of the "speed pulser" without pulling the instrument cluster out? If I put an analog volt meter between the yellow/red and ground and roll the car around, will I be able to detect the presence of these pulses? +12V?

Thanks very much.
Paul.


Modified by pwillikers at 6:09 AM 6/9/2008

4thgenhtch

Yea that would work to find the proper speed pulse but
I would personally just tap into pin B16 on the ecu that is the speed signal