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    1986 Auto Transmission Questions

    The 86 is the "early" 700, and I'm not familiar with it. The TV stuff may be different than what I'm used to working with, but I don't know for sure. TV is ALWAS adjust at full throttle. Sorry. I'm bortingthis ost. The ey-logger icked in and is trning everything to gibberish Ithapens wnte...
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    Shorting pins A and B results in cooling fans on. Normal?

    Shorting A&B energizes all ECM controlled relays and solenoids except fuel pump. The little B4P boost fan on 84-90 is NOT ECM controlled.
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    cooling fan will come on

    There should be 12 volts on the grn/wht wire wih the key ON, engine OFF. If=NO, there's a COOLFAN fuse in the RH dash. 3 amp. This is the fuse for the control circuit. Nw I remember why I do't pst here vdry much. There'sa key-logger orsomething that causes key-stokes to be mssd or omitted...
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    Help! 1987 4+3 manual trans wont go into 3rd or 4th gear

    The OP will never be back or see this, but here's my guess as it happened to me: The adjusting nuts on the 3-4 rod at the transmission lever have gotten loose and the shifter won't "gate" into the 3-4 slot. It can all be fixed from under the car as long as the exhaust is cool. Been there, done it.
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    Running lights

    Do you guys really think that because he's in California, his car behaves differently than every other C4 built? Nonsense. Something is wrong with his switch. The doors shouldn't open until the second position. And they should stay up until the switch is pushed all the way in to off.
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    Help! 92 Corvette - Random rough idle/severe hesitation on start and warm

    I am going to take a wild ass guess based on these symptoms. A: it will ALWAYS start. This tends to rule out optispark and fuel pressure issues. B: "Runs like it's on 4 cyls". Ie, very rough. The EGR valves on the LT1 are negative back pressure. If the valve doesn't seat after engine start, it...
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    1992 Won't Turn Over

    The flashing LED is probably an aftermarket alarm. 3 flashes is a door trigger for a DEI (Viper, Valet, and several other brands). Usually, turning on the ignition cancels the trigger indication. Because yours didn't, I suspect you still have a problem with wiring or something to do with power...
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    4+3 transmission odd behavior

    The overdrive uses the same output and driver in the ECM as the Converter Clutch in an automatic. It seems like you have an automatic transmission PROM. The TCC drops out with zero-throttle, and re-engages after getting back on the gas. Like your overdrive is doing. I don't have an answer for...
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    Question: Brake lights are on all the time

    Some GM's have two switches on the brake pedal. The wire colors for the brake lights are orange and white. So they need to unplug the connector with these wire colors. The switch is self adjusting. Push the brake pedal down a couple of inches. Wiggle the switch, and push it towards the pedal...
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    89 alarm

    The ECM is not incorporated into, nor has anything to do with the alarms system in ANY C4 year. 84-89 the alarm module is behind the radio. In 90-96 the alarm is incorporated into the BCM which is on the transmission tunnel under the HVAC controls. Some years have a separate VATS module for the...
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    89 alarm

    While details of the Vehicle Theft Systems vary from year to year, there is one function that ALL years have: A StarterIinterrupt. If the alarm is triggered, and sounding, it should NOT crank. If it does crank and does or does not start, the starter interrupt relay has been bypassed. The alarms...
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    horn not working

    Do the horns work when you intentionally set off the alarm? If = YES, most of the horn system is functioning. Go to the next paragraph. An 89 has a completely different horn button arrangement than the 90-96. Pull the horn button off gently. It just pulls out. See if the little wire is still...
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    '85 Brake light flickering

    In an 85 there are only two items that turn the BRAKE light on. Fluid pressure differential (master cyl) and the hand brake. 85 does not have ABS, which is also connected to the BRAKE light in 86-up. I'd disconnect the plug on the master cyl and drive it long enough for it to have flickered...
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    1990 HEI Injector Fuse Rating Question - Vin 8

    Both of these circuits are hot in RUN and START. In other GM models these circuits are called ECM1 and ECM2. Or ECM A and ECM B. There are items on these circuits other than just the injectors. O2 sensor heaters, solenoid coils, stuff like that. Perhaps one circuit has a higher load than the...
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    Vehicle thinks the key is in the ignition

    There is a simple test to verify that the "key in ignition" switch is the culprit: With the key out of the ignition, one door open, lock the doors with the power locks. Open a window so you don't lock the keys in it. Close the door. The BCM unlocks the locks when a door closes with the key in...
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    wheel authenticity question

    OEM wheels should have the "JWL" logo visible on the outside. Many aftermarket "ZR-1" wheels are "Autum Fleet Sales", they are made in Japan, and usually have "AFS" on the back side. The OEM "ZR-1" wheels I'm familiar with are "A-Molds" and have that designation cast into the back side. Early...
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    1985 4+3 Overdrive: very specific problem

    I asked this same question on another forum. A respondent there said that he had had two apart that had failing thrust washers. This washer is behind the direct clutch pressure plate. If it hangs up in the case because it is getting deformed, it can cause the "freewheel" I'm experiencing. He...
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    C4 Mufflers

    Drone is caused by two different, but very close frequencies (pitches) interacting with each other. Two functional outlets on the same muffler, but different lengths from the inlet of the muffler will "speak" at different pitches. Drone. A twin engine aircraft or boat that doesn't have the...
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    1985 4+3 Overdrive: very specific problem

    I've owned my 85 4+3 since new. I know how it typically behaves. This Summer, I drove it 5,800 miles in 11 days in quest of a Sam Folz Award in NCRS. The car behaved fairly well considering it was driven further in two weeks than it had been in the previous 20 years. On the last day, the...
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    Question: Trasmission shift points

    84-85 4+3 DO have a TV cable. The 86-88 do not. I have no idea how to set it even though I've owned an 85 4+3 for 32 years. Never had to mess with it. NEVER "adjust" shift timing, feel or quality in the automatic with the TV cable. There is only one correct setting for it. The TV setting...
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