My '89 Justy "check engine light" comes on after 1 minute of start-up, then stays on. Esteban told me in a PM that the connectors to read the ECU codes was under the dash, near the hood release lever. I don't see any unconnected connectors down there. Maybe someone has already connected them and left them that way. But if they did, shouldn't I be seeing the flashing light on the dash with long, then short pulses? The car runs great, but it still bugs me to think something is wrong, so I don't want to ingnore the problem. From what I've read, the '89 is a little different than the other Justies, in fact one place said the connectors for that year are on the engine side of the firewall. Anybody out there know for sure???? I may just take a drive to the dealer and see if they can help, but I don't want to pay them the big bucks to read a simple code for me. At least not yet. Thanks for any help.

Jack

what are the symptoms

Erik, it has no symptoms, it runs great. It's just that the check engine light comes on and stays on. That's telling me something must be wrong. I know some people drive cars for thousands of miles with the check engine light on, but I would really like to know why it's on. I didn't mention it in the first post, it is a carburated, 5 speed manual tranny, GL model with the push-button 4-wheel drive.

Jack

I have an 88 and after I ressurected it, I had problems with the check light being on. I started tracing out the vacuum lines throughout and replaced everyone. I have`nt had a problem since...

I also suspected vacuum line leaks, and did find and repair one about a week ago. The rest of the lines look OK, but that is always a possibility on an older car with gobs of lines. Thanks for the tip.

OK, I have the '90 FSM (just came in the mail yesterday--thanks SVXpert!) which indicates that there should be a black male, black female, green male and green female cluster of connectors under the dash. These should be disconnected for U-check (normal user mode). To read the codes you'll need to connect the "Read memory connectors" (the set of black connectors) and leave disconnected the "Test mode connector" (the green ones). If you have no trouble, your oxygen monitor light should remain off and your Check Engine light should start blinking. If there is a problem, the CEL will remain on and the oxygen monitor light will throw all the trouble codes in memory.

 

I think your problem is that someone connected a set of normally-disconnected jumpers. Unfortunately I only have the '90 FSM, so if yours are located elsewhere I can't be of much service. I do have the code listing though.

Andrew, I just found where I read that the '89 models have the connectors in the engine compartment http://usmb.net/repair/?CurrentDirectory=FOLDER_3f29b58f4430b8.49200047/&FileType=Article&File=ARTICLE_3f2c055f4862e9.39782181.art

I do see some connectors there, but they don't mate up, so I'm still at a loss. Tonight while I was driving the car the CEL started flashing, but it was not a code just a constant on off on off, no variation in the flash length, so it was not a code. Tomorrow, I am going to swing by the dealer and see if they will let me look at the '89 factory manual.

Jack

the connecors are between the hood release cable and the ecm towards the fender side of the clutch pedal

the read memory connector has a LgW wire in pin 21 of the 22 pin harness

the test mode connector has a GW wire in pin 22 of the 22 pin harness

Idaho,,

Check your PM message.

OK, as near as I can tell the underdash connectors are already connected. The CEL does not flash a code, but the O2 light on the ECU does sometimes flash two codes, 24 and 63. I got 10 precious minutes looking at the factory service manual today at the dealer. The 24 code is "idle-up solenoid valve". The 63 code is "idle-up system". At least they appear to be one problem and not a serious one at that. Since the car is running fine right now, I'm not going to worry about it. It doesn't seem to be a problem that will hurt anything. Thanks everyone for helping me with this.

with both test mode and read memory connectors connected, idle speed should be set to 800 +/- 50

 

with test mode connectors connected, ignition timing should be set to 5 degrees +/- 2 degrees below 1000 rpm

 

"NEXT TIME ASK TO SEE THE D-CKECK REFERENCE BOOKLET"

I have one and have been using it for all info provided

got ? ask!

After you have finished working on it , disconnect the battery for awhile & ALSO diosconnect the 2 plugs under the dash .If light comes back on, try to read the codes again, like previously described.

I disconnected both underdash connectors (one black and one green), disconnected the battery for a few minutes, then hooked the battery back up. Started the car, and within a minute the CEL came on. I was able to read a code, 32 (O2 sensor) from the light on the ECU. I then shut off the car, reconnected the black connector, and turned the ignition switch to the on position. The CEL light came on, but did not flash a code. So it now looks like I need an oxygen sensor, but I still don't know why I can never get a code to flash from the CEL. Maybe something to do with this model year?

You should be able to get a code to flash with the harnesses connected & the switch in the " on " position. I had one Justy with a bad computer that left the light on, but there were no codes stored. It ran great so I lived with it.You can buy an inexpensive 02 sensor, universal, that will work fine, by just splicing the wires. I, also, have cleaned one with carb cleaner & a brass brush, & that made it work properly. A poor 02 sensor will usally make it run rich, & gas mileage will plummet!