Hi, new to the group but have read threads for years, the issue I have is the lead to the air conditioning compressor wore through the insulation and grounder out. what I have now is the radiator fan for the air conditioning runs constant, climate control all the green light work when you press the buttons but nothing else goes. checked all the fuses both sides all good. scrolled through all 37 levels on the climate control and came up with
1-67
2-96
3-73
4-198
5-188
6-01
7-00
9-00
10-00
11-00
12-155
16-89
17-128
19-91
20-96
21-144
22-108
23-128
24-152
30-47
31-166
34-153
35-155
36-00
37-00

did all these readings after i disconnected the battery, not a very good wrench any help would greatly be appreciated

John 1993 corvette standard coupe, whit,e lt1, auto, 58,000 miles

 

If the AC Clutch fuse is ok, try replacing the AC clutch relay. If the line to the compressor is open somewhere, a trouble code will set (usually 69) and the cooling fan(s) will run.

 

Thanks for the input will check those items out and I'll get back to you

again thanks

John

 

You did not post parameter 0 which are HVAC system faults.

What color was the wire that shorted out?

Are you saying all HVAC functions work except the AC Clutch doesn't engage?

You need to pull any ECM codes by doing the following.
Take a piece of wire or paper clip and connect pin A to pin G on the diagnostic connector located above the drivers right knee.

Turn the ignition on. Do not start the engine.

The engine fans will come on.

Look at the dash cluster LCD.
Should see any trouble codes if there are any displayed on the LCD.
Module 1 is the CCM
Module 4 is the ECM
Module 9 is ABS

Pin out for the diagnostic connector looks like this.

 

Im back, was down for a couple days,
it was the green wire that grounded out, for now i just slide the gray insulation that covers the green and black wire over the worn through spot

-00 on climate control had no codes

as far as the climate control all the buttons turn green when you push them
push auto the green light comes on for that and above the fan speed
setting temps inside you can do also reads out side temp
fan speeds led goes from 1 to 10
but other then that you get none of the buttons functions

ill do the A and G thing Saturday

thanks for the help

John

 

I'm assuming when you increase or decrease the blower motor speeds the blower
motor works.

There are basically two fuses used in the HVAC system.
Both fuses are located in the passenger side end of dash fuse panel.
Verify the fuses are good.
AC Prog 5 amp fuse. Hot all the time
AC Clutch 10 amp fuse. Hot with ignition On

If the Dark Green wire shorted to ground and the AC clutch was engaged it would blow the AC Clutch fuse which I doubt is blown because it powers the HVAC Control head and HVAC Programmer.

Disconnect the negative battery cable for a couple of seconds then reconnect it. This will clear any codes.

Turn the ignition On.
The radiator cooling Fans should not run.
The HVAC system will go thru and re-calibrate the blend door position which takes about 20 seconds.
After it's done the blower motor will come On.
Use the off button to turn the blower motor off.
Start the engine and see if everything functions normally.

 

no the blower does not come on or change speeds, we went through all the fuse there good,
i'll disconnect the battery and then go through all the codes on the climate control and the jumper a to g and get back with you this afternoon, baby sitting my grand son lol

thanks for everything john

 

hooked up the battery, here are the values from the climate control
00
1 77
2 124
3 82
4 196
5 174
6 01
7 thru 10 is 00
11 98
12 175
16 36
17 128
19 98
20 123
21 127
22 -152
23 128
24 158
30 49
31 162
34 158
35 -155
36 an 37 00

now for codes on the gauge cluster

1 c12
4 h68
9 ---
1.0

all the fuses are good hope this is detailed enough, the fan on the driver side of the radiator still comes on every time you start it

thanks guys for all the help john

 

So you disconnected the battery cable to clear the codes?
Then you pulled the codes and code 68 set again?

PCM code 68 is the ECM is detecting a voltage on the Dark Green wire
(the one that the insulation was worn off) when AC is not requested.

Unplug the connector at the AC compressor clutch.
Turn the ignition On.
Make sure AC is OFF.
At the disconnected connector use a test light or volt meter and measure the voltage from the Dark Green wire to the Black wire.
You should measure 0 volts DC.
If you measure 12 volts.
Unplug the AC Clutch relay.
If you unplug the AC Clutch relay and the 12 volts goes away, the relay Normally open contacts are stuck closed or there is 12 volts on the Dark Green/White wire coming from the PCM which is energizing the relay when AC is not requested.

The AC Clutch relay is mounted on the Passenger side wheel well
black plastic housing.

If you have an automatic trans. there will only be one relay.
The relay will have four wires going to the relay socket. Two Brown wires, Dark Green/white and Dark Green.

If you have a manual transmission there will be two relays in that area. You can identify the correct relay by the color of the wires at the relay socket.

As for the Blower motor not working.

On top of the evaporator housing under the hood are two electrical plugs.

One plug has the following colored wires.
Tan wire. The DC voltage should vary as you change blower speeds.
Purple wire is the voltage going to power the blower motor.
Black wire is Ground.

Other connector has a Red wire and is 12 volts to power the Blower Control Module and is Hot all the time.

So when you turn the blower on, you should measure a DC voltage on the Tan wire. The voltage should change depending on blower speed selected.

In turn the Blower Control Module outputs a proportional voltage to power the blower motor.
You can measure this DC voltage on the Purple wire that goes to power the blower motor.

 

i want to thank everyone for the clear and great trouble shooting, ill work on this the next couple days and get back with you

Thanks For All The great help!!!!!!

John

 

unplugged the compressor turn the key to on no voltage, couldnt locate ac clutch relay ill google location but couldn't find it in the passenger side wheel well, get back with you Friday

Thanks John

 

Hi Im back, still can't locate the ac clutch relay, there's some kind of module with a small computer board attached to the blower motor housing , looked through the forum's not having any luck with that either. is it behind the knee kick plate inside the passenger side. any help would be great.
sorry for the delays in between your post and me working on things disabled only good for a couple hrs a day and as my wife keeps reminding me there's more to do then work on my car all the time. thats the pg version

Thanks John

 

found the relay under the heater core hoses behind my nitrous purge sol
Thanks Guys dug through forum threads more and found it was mounted to the wheel well looked for screws in the wheel well and thats how I found it also pulled the car out of the garage had better lighting, try to get back to work on it tonight

Thanks Again

 

Assuming the engine temperature is below the radiator fan turn on temperature.

When does the radiator fan come on? After you turn the ignition On or after you start the engine?

Clear the codes again by disconnecting the negative battery terminal for 10 seconds then reconnect the cable.

Disconnect the AC compress clutch connector.
Remove the AC Clutch relay.

Turn the ignition On.

Let the HVAC system re-calibrate the blend door position which takes 30 seconds. During this time you should hear the blend door motor moving the blend door.

Turn the HVAC off.

Start the engine and let it run for a couple of minutes.
Does the fan come On which would signify code 68 has set.

If the fan comes on pull the codes again and see if 68 is set for module 4.

 

Hi, we did DTC 68 RELAY CIRCUIT
codes that came up where

1 H41
H54

4 H28
H68

9 ---

10
That was the result, what I take from the test is the ecm is bad, but what does the rest of the codes come from ?

Again thanks a lot for the information you guys are great John

 

the fan comes on as soon as you start the car, we did DTC 68, list of codes where
1. H41
H54

4. H28
H68

9. ---

10.

I'll do the last message I got Saturday

thanks for all the help John

 

Module 1 CCM H41 is a serial communication problem between the CCM with the ECM. (The CCM is the master on the serial bus).

Not sure what caused the 41 but the HVAC Programmer is also on the serial bus.

Module 1 CCM DTC 54 was set because of 41 which disables the pulsing of the fuel injectors.

Module 4 ECM DTC 28 was due to the AC Clutch relay being removed.

You said the HVAC blower motor doesn't work?
Did this problem happen at the same time you discovered the shorted Dark Green wire?

I would trouble shoot the no blower motor fan working problem and get that working and see if that resolves the other strange problems.

Scroll back to post #9. I posted the schematic for the blower motor and how to test the circuit.

 

yes lost air conditioning,climate control ( buttons still light up fan speed still scrolls other then that none of the functions on the climate control ), and radiator fan staying ( while the car is running ) on driver side fan at the same time, will try to get back to everything
Sunday.

Thanks for all the help John

 

Hi sorry I was gone for a week health but im back

we checked both plugs on top of the evaporator and have the following

red wire has 12 volts running to it
tan wire dc voltage is varying as you change fan speed at 4 and reading 6.9 volts
purple wire has power going to it 5.8 volts
black wire has no ground
and the compressor has no ground or power going to it

ps. if I get a remanufatured ecm do you have to have it programed for your car
Again thanks for all your help John

 

Well you may have found your problem.
G109 is the Ground for the AC Clutch coil, the Blower Motor Control module, the Blower Motor, the windshield washer pump motor and low oil level sensor.

G109 is located on the passenger side frame rail.

Either there is corrosion at the bolt to frame or the Black wire is open some where.

You can visually follow the Black wire at the connector on the evaporator housing or the Black wire at the Blower Motor power connector and verify where the problem is.

If you have continuity from the Black wires to the frame then look at the negative terminal of the battery. One wire from the negative battery terminal goes to the frame rail on the driver side below the battery area. Near that area should also be a braided ground wire from the frame to the driver side transmission bellhousing stud. If the engine or transmission has ever been removed that braided wire at the bellhousing stud is sometimes left off by mistake.

If you replace your ECM you remove the little circuit board inside the ECM that contains the Eprom and plug it into the replacement ECM.