Since the search engine is disabled, I will ask this question...Has any one had the problem of not being able to clear trouble codes, even after disconnecting the battery for more than 24 hours AND the ECU stays in Mode III. I have changed out the ECU and still had the same results
I am the original owner...125k miles and I am not a novice at working on cars. Any suggestions

Telfonejac

 

Only certain codes are erased. Like ignition signal, TPS, stuff like that.
What code is it giving you. Some problems are more foregiving then others, so the reset will just give you the same results until the problem is tracked down and fixed.

 

My problem is no codes are cleared and the ecu will not switch to other Modes...and I have changed out ECUs and had the same results. My problem was a bad crankshaft/camshaft sensor and it was corrected. My ecu shows 11-12-21-23-31. But those problems have all been CORRECTED. An ECU that has been "cleared" should not display any codes until the engine has been started... and yes I swapped out ECUs with one that had not had any battery applied for months, it should have been void of codes. I may have a wiring problem


telfonejac

 

If the ecu won't switch to another mode maybe its the problem. Maybe through some horrible coincidence you got two bad ECU's. You sound like you know what your doing. If you fix the problem, and reattach the ECU usually thats all it takes.

Some of those codes I recognize, TPS valve switch code 11. Isn't 31 the bad ECU code? Or is it 33? I don't have the manual with me right now Ill post it later.

 

You may be right Drjmaxx88 about the ECUs. May be I did get a bad one. Both ran the car just fine...I'll check it out
Thanks

telfonejac

 

11 is crank angle sensor
12 is air flow meter
21 is ignition signal
23 is idle switch
31 is ECU

Sorry about the mix up
These are out of the 88 FSM.

Thanx sarin

 

Alright. Time for me to step in before this goes too far in the wrong direction. One thing not mentioned here. 85-86's have a totally different ECU programming. So pulling codes is different. There isn't 5 different modes to work with like the 87-88's. Just normal operation (with open/closed loop), and diagnostic. The codes return are read the same, and are similar:

11: Crank Angel Sensor
12: MAF Circuit
13: CHTS
21: Ignition Signal
22: Fuel Pump Circuit
23: TPS
31: Load Signal Circuit
32: Starter signal
41: Fuel Temp Sensor
44: All good, no codes

By default, when you start the diagnostics, the car will always come up with codes 23 and 31. During the process these will clear unless they are actually bad.

So here is the process:

1. Verify mode selector is fully counterclockwise.
2. Turn Ignition to on.
3. Make sure inspection lamps are both on. (If not, check battery source, if that is fine, replace ECU)
4. Turn mode selector fully clockwise.
5. Depress accelerator completely, then release.
6. Start Engine
7. If automatic, apply brakes and shift into drive, manual leave the car in neutral.
8. Turn a load switch on then off (power steering, a/c, heater blower, headlights, rear defogger, or radiator fan switch)
9. If automatic, shift back to park.
10. Read off codes. If no codes, you should get code 44.
11. Turn mode selector fully counter clockwise.
12. Turn off motor.
13. Complete.

To clear codes:
1. Turn ignition to on.
2. Turn mode selector fully clockwise and leave it there for 2 seconds.
3. Turn mode selector fully counter clockwise and wait 2 seconds.
4. Turn ignition off.

max88q: Can you please sticky this post?

S

 

Thanks Maxmase66

That is making more sense as to how my ECU is displaying codes. My 86 is little different then the Chilton's manual describes. Even on the front struts, I started to change out what I thought was a bad cartridge and to make it easier I decided to change the complete unit with a junk yard replacement The junk yard unit came off of a 86 SE, I was present when it was removed, but it would not fit my 86. The the strut mounting on the spindle is about 1/4 inch wider on mine then the replacement was. Of course it would not fit. My SE has a manufacture date of Sept-85. The salvage yard owner thought I was crazy when I told him that manufacture date has a bearing on some parts of the 86 Max SE. Most parts books refer to the date of manufacture as a criteria for selecting the correct replacement part. As it turned out the electrical contacts in the cartridge tube were bent out of shape and were not making connection, I straightened up the contacts, replaced the harness connector and surprise...surprise it worked!. I could not see the problem until I removed the strut and could see clearly down into the shaft where the pins were. SO I am not surprised that the ECU is different. By the way thats a GOOD LOOKING SE you have there.
THANKS AGAIN Maximase86

telfonejac