Trouble Codes, Accessed in the Climate Control, other neat info

Did you know that you can access your Engine(and other) trouble codes thru the Climate Control? Did you also know that you can accurately monitor the engine RPM, vehicle speed, coolant temp, and others? If so, good job! If not, look at this! 😉

This is for 94-96's!!​

*Please note, some of this was info copied directly from ISSF.



Instructions for putting ACC in diagnostic mode -
- turn ignition to ON position (or start vehicle)
- press and hold the "temp up" and "OFF" buttons at the same time until the unit does a full segment check.
- Release the buttons.
- Display should read -00... you are now in diagnostic mode
- Using the fan up/down buttons, select desired function from above
- press the "middle" Button. It should be in the top right corner on the CC.
- To Exit the trouble code area, and go back to the -00 display, hit the "Middle" button again.

Have fun!

You will see -00. You can change the funtion(it will say -01, -02, etc) with the fan up, and down buttons. Here is a list of what all the -00 numbers mean.


Here are the most common you will need to know

-00 PCM diagnostics codes
-01 CCM Diagnostic trouble codes
-02 HVAC Diagnostic trouble codes
-03 SIR Diagnostic trouble codes
-04 ABS/TC Diagnostic trouble codes
-06 Engine RPM
-14 Vehicle speed
-24 Coolant Temp (°C) - Reading taken at the Water Pump sensor, This is what the PCM uses to control the fans.


Quoting Scott Mueller:
"B/D-car coolant fans operate under PCM control at the following engine temperatures and A/C system pressures:

Fan………………Mode……Temps………………A/C Pressure
Primary (RH)…ON…… 109°C / 229°F……189 psi
Primary (RH)…OFF……105°C / 221°F……150 psi
2ndary (LH)……ON…… 112°C / 234°F……240 psi
2ndary (LH)……OFF……108°C / 227°F……210 psi

Additionally, the PCM will turn off the fans at higher vehicle speeds (above 48 MPH I believe), since running fans can actually impede airflow through the radiator at high speed.
Each fan also has a minimum running time. Once activated, the primary fan will run for a minimum of 50 seconds, and the secondary fan for a minimum of 26 seconds.
Finally, certain Diagnostic Trouble Codes (DTCs) may cause the PCM to turn on one or both fans."


Diagnostic Pointers and Parameters

No. Description Range Default Value Units


-00 PCM System Diagnostic Trouble Codes ...............................................
-01 CCM System Diagnostic Trouble Codes ...............................................
-02 ACAC (HVAC) System Diagnostic Trouble Codes .......................................
-03 SIRSystem Diagnostic Trouble Codes ................................................
-04 ABS/TC System Diagnostic Trouble Codes ............................................
-05 Program number .......................... 0-255 ....... n/a ............. Counts
-07 Command Blower Motor Speed .............. 0-128 ....... n/a ............. Counts
-14 Vehicle speed ........................... 0-199 ....... n/a ................ MPH
-15 HVAC Learn Mode (Temp Cal) .............. -5 to +5 F .. 0 F ............ Degrees
-18 Sun Load Sensor ......................... 0-255 ....... n/a ............. Counts
-20 Current Temperature Valve Position ...... 0-255 ....... 240 ............. Counts
-22 Temperature Valve Position (Full Cold) .. 180-250 ..... 180 ............. Counts
-23 Temperature Valve Position (Full Hot) ... 5-60 ........ 60 .............. Counts
-24 Engine Coolant Temperature .............. -40 to 151 .. n/a ............ Celsius
-25 Command Temperature Valve Position ...... 0-255 ....... 128 ............. Counts
-27 Air Delivery Mode ....................... 0-9 ......... n/a ... Code (see below)
-28 Inside Air Temperature Sensor ........... 0-255 ....... n/a ............. Counts
-31 Outside Air Temperature Sensor .......... 0-255 ....... n/a ............. Counts
-37 EEPROM Revision Number .................. 0-0000 ...... n/a ............... Code

Here is a list of the trouble codes. These were posted for the Fleetwood, so some might be slightly different, or not apply.


PCM diagnostics codes... (-00)

11: malfunction indicator lamp (MIL) circuit
13: Bank 1 (left) heated o2 sensor (open circuit)
14: Engine coolant coolant temperature sensor (siganl voltage low, high tempurature indicated)
15: Engine coolant coolant temperature sensor (siganl voltage high, low tempurature indicated.
16: Distributor ignition system (low resolution pulse)
18: injector circuits.
21: Throttle position sensor TPS circuit (signal voltage high)
22: Throttle position sensor TPS circuit (signal voltage low)
23: Air intake temperature IAT sensor circuit (signal voltage high, low temperature indicated.
24: Vehicle speed sensor (VSS) circuit.
25: Air intake temperature IAT sensor circuit (signal voltage low, high temperature indicated
26: Evaporative emission (EVAP) canister purge solenoid circuit.
27: Exhaust gas recirculation (EGR) vaccum control signal solenoid valve circuit
28: transmission range (TR) pressure switch assembly fault
29: Secondary air injector (AIR) pump circuit.
32: Exhaust gas recirculation (EGR) 1 of 2
33: Manifold absolute Pressure (MAP) sensor circuit (signal voltage high- vacuum low)
34: Manifold absolute Pressure (MAP) sensor circuit (signal voltage low-vacuum high)
36: Distrigutor ignition system (faulty high resolution pulse or extra low resolution pulse detected.)
37: brake switch stuck on
38: brake switch stuck off
41: Ignition control (IC) circuit (open)
42: Ignition control (IC) circuit (shorted or grounded circuit)
43: Knock sensor (KS) circuit
44: Bank 1 (left) heated O2 sensor circuit (lean exhaust indicated)
45: Bank 1 (left) heated O2 sensor circuit (rich exhaust indicated)
46: PASS-key II circuit
47: Knock sensor circuit or control module missing.
48: Mass air flow (MAF) sensor circuit
50: system voltage low
51: EEPROM programming error
53: Sytem voltage high
55: Fuel lean monitor
58: Transmission fluid temp. (TFT) sensor circuit low (High temperature indicated)
59: Transmission fluid temp. (TFT) sensor circuit high (Low temperature indicated)
63: Bank 2 (right) Heated oxygen sensor(HO2S) circuit (open circuit)
64: Bank 2 (right) Heated oxygen sensor(HO2S) circuit (lean exhaust indicated)
65: Bank 2 (right) Heated oxygen sensor(HO2S) circuit (rich exhaust indicated)
66: A/C pressure refrigerant circuit (open or shorted)
67: A/C pressure refrigerant circuit (pressure sensor or A/C clutch circuit problem)
68: A/C relay circuit (shorted circuit)
69: A/C clutch circuit
70: A/C clutch relay driver circuit
72: vehicle speed sensor loss
73: Pressure control solenoind (PCS) circuit (current error)
74: Traction control system (TCS) circuit low
75: Transmission system voltage low
77: Primary cooling fan relay control circuit (not used with V08 option)
78: Secondary cooling fan relay control circuit
79: Trsnsmission fluid overtemp
81: Transmission 2-3 shift solenoid circuit
82: Transmission 1-2 shift solenoid circuit
84: Transmission 3-2 control solenoid circuit
85: Transmission TCC stuck "ON"
90: Transmission TCC solenoid circuit
95: Change oil lamp circuit
96: low oil lamp circuit
97: VSS output circuit

CCM Diagnostic trouble codes (-01)

20: RAP enable circuit (circuit shorted to battery)
21: RAP enable circuit (circuit open or shorted to ground)
22: DIL enable circuit (circuit shorted to battery)
23: DIL enable circuit (circuit open or shorted to ground)
24: Curtesy output circuit (circuit shorted to battery)
25: Curtedy output circuit (circuit open or shorted to ground)
26: VES output circuit (circuit open or shorted to ground)
27: VES output circuit (circuit shorted to battery)
28: VES tracking tracking error (circuit open, shorted to ground, or shorted to battery)
30: "PASS KEY FAULT" telltale circuit (circuit shorted to battery)
31: "PASS KEY FAULT" telltale circuit (circuit open or shorted to ground)
32: Fuel enable circuit (circuit shorted to battery)
33: Fuel enable circuit (circuit open or shorted to ground)
34: Heaflamp enable circuit (circuit shorted to battery)
35: Park lamp enable circuit (circuit shorted to battery)
36: DRL enable circuit (circuit shorted to battery)
37: DRL enable circuit (circuit open or shorted to ground)
38: EEPROM calibration error
39: EEPROM calibration id error
40: Delay pot circuit (circuit shorted to ground)
41: Dealy pot circuit (circuit open or shorted to battery)
42: Key resistor circuit (circuit shorted to ground)
43: Key resistor circuit (circuit open or shorted to battery)
44: Steering wheel sensor circuit (circuit open or shorted to ground)
45: Steering wheel sensor circuit (circuit open or shorted to battery)
46: CCM internal failure
47: Canadian select input error

HVAC Diagnostic trouble codes (-02)

01: Outside air tempurature sensor circuit (circuit open)
02: Outside air tempurature sensor circuit (circuit shorted)
03: In car air tempurature sensor circuit (circuit open)
04: In car air tempurature sensor circuit (circuit shorted)
05: Sun load sensor circuit (circuit open)
06: Sun load sensor circuit (circuit shorted)
10: Air mix motor circuit (circuit open)
11: Air mix motor circuit (circuit shorted)
26: Serial Data Communication (circuit shorted to battery, shorted to ground, or circuit open)
27: Invalid EEPROM detected

SIR Diagnostic trouble codes (-03)

15: Passenger deployment loop resistance high
16: Passenger deployment loop resistance low
17: Passenger deployment loop open
21: Driver deployment loop resistance high
22: Driver deployment loop resistance low
24: Deployment loop voltage low
25: Deployment loop shorted to ignition
26: Driver's deployment loop open
35: ADS (auxiliary discriminating sensor) missing/shorted to ground
36: ADS closed/shorted to voltage
51: Frontal crash detected
52: Crash data area full
61: Lamp circuit failure
62: Redundant lamp circuit failure
71: Internal SDM malfuntion

ABS/TC Diagnostic trouble codes (-04)

21: RF wheel speed sensor circuit malfunction
23: RF wheel speed sensor circuit continuity malfunction
25: LF wheel speed sensor circuit malfunction
27: LF wheel speed sensor circuit continuity malfunction
28: Wheel speed sensor circuit frequency malfunction
31: RR wheel speed sensor circuit malfunction
33: RR wheel speed sensor circuit continuity malfunction
35: LR wheel speed sensor circuit malfunction
37: LR wheel speed sensor circuit continuity malfunction
41: Right front valve soleniod malfunction
42: RH outlet valve solenoid malfunction
45: Left front valve solenoid malfunction
46: LF outlet valve solenoid malfunction
47: ASV prime line solenoid malfunction
48: USV pilot valve solenoid malfunction
51: Right rear valve solenoid malfunction
52: RR outlet valve solenoid malfunction
55: Left rear valve solenoid malfunction
56: LR outlet valve solenoid malfunction
57: TCC disable relay output malfunction
58: EBTCM internal adjuster assembly malfunction
61: Pump motor or pump motor relay malfunction
62: Traction disable switch used or RPM signal malfunction
63: valve solenoid relay malfunction
64: Throttle position signal malfunction
65: Adjuster assembly circuit malfunction
66: Adjuster assembly control malfunction
67: Throttle position sensor comparison malfunction
71: EBTCM internal malfunction
72: Serial data link malfunction
73: Spark retard monitoring malfunction
85: Low voltage.

Here is a link to both info sources used.

http://www.impalassforum.com/vBulletin/showthread.php?p=2034815#post2034815

http://www.impalassforum.com/vBulletin/showthread.php?t=183831

Here are links to Online listings of trouble codes, incase these are off.



Here is a list of trouble codes.

OBD-I codes 95 -

http://www.troublecodes.net/GM/95_57P.shtml


OBD-I Codes 94 -

http://www.troublecodes.net/GM/94_57P.shtml

OBD-I Codes 93

http://www.troublecodes.net/GM/93_577_tbi.shtml

OBD-I Codes 92

http://www.troublecodes.net/GM/92_577_tbi.shtml



OBD-I Codes 91


http://www.troublecodes.net/GM/91_577_tbi.shtml

-08 Coolant Temp (°F) - Reading taken at Cylinder head sensor, typically 20* cooler than the -24 reading


I don't think that's accurate really. My exhaust manifold decimated the signal wire to the coolant sensor in the head, and the ECC would still read properly. I left it unplugged and it still read it.

You know, I was just thinking about that. On my red RMS, the sensor is completely broken off. I completely forgot, and was driving, keeping an eye on the -08... it read 180* when I checked it. Wouldn't one of them be Trans Temp?

That would make sense. Suppose -08 is water pump, and -24 is trans temp?

I may unplug the WP sensor and see what the ECC does tomorrow. 🙂

-06 engine RPM

Thanatos said:

That would make sense. Suppose -08 is water pump, and -24 is trans temp?

I may unplug the WP sensor and see what the ECC does tomorrow. 🙂

Click to expand...

Easy way to tell. Monitor on a cold start without moving. Coolant readings will go up, but trans won't.

Griswold said:

Easy way to tell. Monitor on a cold start without moving. Coolant readings will go up, but trans won't.

Click to expand...

Yes it will. The pump is still sending fluid thru the converter, and the trans. Also, the fluid is still going to the cooler inside the radiator, which is actually warming the fluid at this point. My 96 caprice 9c1 has a gauge that reads engine temp, and also trans temp, by the flip of a switch. Even just letting it idle, the trans temp goes up. Not as fast as engine temp, but it goes up. If my Roadmaster had one, I could compare the readings.

MrBuick (Magnum) said:

Yes it will. The pump is still sending fluid thru the converter, and the trans. Also, the fluid is still going to the cooler inside the radiator, which is actually warming the fluid at this point. My 96 caprice 9c1 has a gauge that reads engine temp, and also trans temp, by the flip of a switch. Even just letting it idle, the trans temp goes up. Not as fast as engine temp, but it goes up. If my Roadmaster had one, I could compare the readings.

Click to expand...

Yes, you're right. What I meant is it won't go up as fast, so if it is reading trans temp, the difference between the two readings should be greater sitting versus driving.

-08 is indeed at the WP. THe reading defaulted at 173* or something close, when unplugged.

Used the HVAC method to read the codes on the LT1 i swapped into a 85 Electra estate. What i also observed is that -08 & -24 seem to be the same. One is fahrenheit and the other is celsius. Both readings seem to go up together when idling from cold start. Diagrams indicate that the tranny has a temp. feed to the PCM but one would expect the tranny to heat up at a delayed rate because no work is being done at that point and the thermostat has not opened.

As far as I know, there are two temp sensors on this LT1. The ECT sensor and the gauge temp sensor. Only one sends a signal to the ECM, the other sends its impedance to the dashboard gauge; there is no cylinder head sensor communicating with the PCM. Later this week i will observe more thoroughly the HVAC info and maybe borrow a scanning tool.

thanks for the info😀

Interesting, my 08 reading is about 25-30 degrees higher than ambient temperature on start up, even after the car has been sitting several days. At the top end, reads bang on 180 fully warm. Also have a Cobalt - the DIC reads within a degree or 2 of ambient on start up.

Read your codes and engine rpm through the HVAC controller?!!??!!

That is too SWEET!!!

Looks like I don't need a tach anymore, lol.

What is a code 126 under HVAC?

We'll see if anyone can find that. 😉

Dido, i have code 126 also.

Anyone know what it is?

Also showing Code 126 under HVAC codes.

Not sure what the code means, but I can tell you that my heater blows cold air. You guys having any similar issues?

If I pull the plug at the water pump sensor, both 08 and 24 drop.

Plugged in 08 reads 188, as soon as I unplug it, it goes to 0 then after I press the middle button twice it reads 135 and stays there.

24 reads at 99 plugged in and changes to 61 when unplugged.

Both of these are in reference to unplugging the sensor at the water pump only.

i found a broken plastic vacum line (for the climate control) under home plate by number 8 injector. I cleared the codes and we'll see if 126 comes back or if that was it. Everything operates as it should now. 🙂

Hey meltdown definitely keep us updated. I just saw the 126 code also.
Any one have any ideas about the tranny temp? I would really like to keep
an eye on the health of mine.