'93 Accord Cruise Control ECU; which years?

ok, so for the benefit of the group, talk us through your diagnosis and how you concluded it was the ecu.

For my knowledge, where is the ECU?

Thanks

Hmmm, well, first off the cruise control ECU (in a LHD car -left hand drive) is to the left of the steering column blocking the main relay.

As far as my troubleshooting goes, I guess I'm not yet there after all, at least not 100%. I browsed around the internet for a replacement cruise control ECU and the one's I found were "good" for

1990-1993 models. Going on this information I used my 1991 Accord manual for the cruise control diagnostics and followed the steps. There is a table for each wire going into the control unit and I checked them all for either voltage or continuity to GND and almost everything checks out. However, I found some interesting things that I'm having a hard time explaining. If anyone can help that would be great. I have the cruise control diagnostics for a 1990-1991 and a 1994 Accord. The only differences between the '91 and the '94 are 1) an extra wire is used on the '91 model which supplies voltage to the ECU when the engine is running, and 2) the '91 model has continuity to GND when the clutch is PRESSED and the '94 model has continuity when the clutch is NOT PRESSED.

My '93 however has a hole in the clutch where the push-button clutch switch goes right through. It makes no sense that this hole is there, so I'm guessing there was a stopper of sorts that must have fallen out. I plugged it with a screw and when released (NOT PRESSED) I get continuity, which is against what the '91 diagnostics say I should be reading. I must be mistaken that other model Accords have the same ECU, but I don't know which to go on as I am missing my '93 manual. I tried both states and neither fixed my cruise control problem. I checked the diaphram on the actuator and the solenoid relays and they all check out operational. Also, for an Automatic car, this clutch wire is used for the same purpose (can't engage cruise when not in the proper gear: 2, D3, D2). So, I'm curious, as there is no difference in the troubleshooting, if an Automatic ECU can be swapped for a Manual ECU.

Can anyone verify the output of the clutch switch when it is PRESSED and NOT PRESSED for a 1993 Accord? I don't see another switch on the clutch, so I'm curious if this switch also performs the start-check which does not allow the car to start unless the clutch is in. Any help or suggestions is greatly appreciated.

Thanks!

According to the Helm manual for the '93 Accord, the switch is closed (pins B-C) when the pedal is up and is open when the pedal is depressed. The switch for the cruise control is the upper switch, the one mounted horizontally. The lower, angled switch is for the starter interlock. (According to the picture.)

Look around under the mat or carpet for the plug. My Nissan had one of those for the brake lights that fell out. It looked like a phenolic mushroom. If it is missing I'm sure the cruise control won't engage.

Mike

You can compare part numbers for different models and years using

or .

I am a little confused about your wording here. There's the ECU, short for "Engine Control Unit" or similar that's generally located in the passenger side footwell. Short of a flood saturating the inside of the car, these rarely fail.

Do you instead mean the "cruise control actuator"? You'll see a drawing of this under "Auto Cruise" at the sites above.

"scube" wrote

Oops. Helps if one reads the whole thread (plus the server seems a little whacked and is posting messages out of synch).

My Chilton's manual calls what scube describes the "cruise control module" and the "cruise control unit." They appear to be the same thing. I am having trouble locating it at

for a manual transmission. The "Fuse box-Relay" section seems like the best bet.

Hmm, well lower angled switch in my car does nothing to the starter interlock, meaning I can toggle it w/ not change in if my car starts w/ clutch pressed or not. The wires coming from the horizontal switch do not go to the cruise control either. However, the ones coming from the angled switch do goto the cruise control. I looked at the diagram for the '91 and it is hard to distinguish which switch the arrow is actually pointing to. Another note is that this '91 manual says that pins A-B are open when pedal is pushed (push-button is out) and closed when released (push-button is in). There is no mention of pin C, though it is a three position connector, so maybe the manuals refer differently to the pins in question. This is how the pinout is for the '91 Accord (lock tab is facing up) __||__ |x B A| ~~~~~~ With the far left terminal not in use. I'm still confused as to which switch it is, but deduction tells me it is the lower angled one. Any light someone could offer would be appreciated. Thanks for your input Michael!!

I think I've found a problem w/ an intermittent brake switch. I pulled it out and it worked, but when I put it back in it would work frequently (no problem w/ my brake lights though...??). I'm hoping that when I fix these two things my problems will go away, but I rigged them up to work and it still didn't.

Does anyone see a problem w/ using an Automatic cruise control unit on a manual? As I stated above the diagnostics are indifferent to which style it is, I'm just curious if there is some different operation from the Control Unit which would be impacted by the type of transmission in the car. It all seems straight forward: The wheel rotation is reported to the vehicle's cruise control unit and the control unit adjusts the actuator to keep that speed constant. Am I missing something?

Thanks all...

Ahh, yes! I finally got the cruise control to engage and actually affect the velocity of my car!! My results:

First, the brake switch is faulty. I pulled it apart and fiddled with the solder connects. It works now, but I don't know for how long. Second, my adventures with my clutch pedal also had an effect on the operation. My "pedal pushed" switch was not engaging.... The cruise control thought my clutch pedal was always depressed. The pedal was missing a stopper and so I plugged the hole w/ a screw.

From my findings, in my 1993 Accord, the lower angled clutch switch is for the cruise control. That was good because it would be a mission to get to the other switch!!

Thanks to you all for your input and questions, this dog will finally hunt again!!

Thanks for the feedback, and congratulations on the triumph!

Mike

Seconded!

Thanks for the encouragement guys. Thanks goes out to all the helping friendly users of this NG. I'm glad to have my cruise control back!!

... join me next week in the adventures of diagnosing my ABS issues...

scube