Question about 1998 Chevrolet K1500

1 Answer

Ac not working

I am trying to find out if there is a way to test for PCM problem causing the ac not to work. symptoms. NO control over the doors that move air from floor to upper vents. AC button will not engage clutch on compressor. Fans operate. freon level good. I bypassed the relay that engages compressor clutch and it will engage. It seems to be leading to the computer.

Posted by on


1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 20 achievements.


    An expert that got 10 achievements.


    An expert that got 5 achievements.

  • Chevrolet Master
  • 22,265 Answers

If you by passed the relay and clutch engaged then this shows that pump works ??but was it getting cold on and around the restrictor valve where the pipes enter the cab is normally a valve block but american monsters use a valve in the pipe for cooling and if its not getting cold their or blowing cold inside cab then system needs re-gassing with R 134 gas if its an older system with R 12 gas then it will need to have adaptors fitted to valve connections and refilled with R134 gas.The main cause of A/C system loosing gas is porosity in the rubber flexible pipes also the back seal on the pump.Or just regass and put a leak stopper in the system

Posted on Nov 04, 2008


1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya Mechanic can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repair professionals here in the US.
click here to Talk to a Mechanic (only for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017


Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

I believe I have a loose/dirty electrical connection related to my cruise control on my 2006 Mercury Milan. Where are the connections exterior of the cab that I can check?

You have no idea what's up , all computer controlled ! The cruise control switches are input's to the PCM - engine computer ! There is no pressure sensor near the master cylinder for the CC . The vehicle has ETC - electronic throttle control . Your best bet ,take it to a qualified repair shop.
Here is a web site for free wiring diagrams Enter vehicle info. year , make , model an engine size . Under system click on engine ,then under subsystem click speed controls . Click the search button ,then the blue links one at a time .
Speed Control The speed control system consists of the following components:
  • Speed control switches
  • Speed control deactivator switch (part of the stoplamp switch)
  • Stoplamp switch
  • Clutch pedal speed control deactivator switch (manual transaxle)
  • Speed control indicator
  • Powertrain control module (PCM)
Principles of Operation
The speed control system is controlled by the powertrain control module (PCM). The speed control system is designed to maintain a selected vehicle speed between 48-200 km/h (30-124 mph). The speed control system is controlled by the steering wheel mounted switches (ON, OFF, SET+, SET- and RESUME), the stoplamp switch, the clutch pedal speed control deactivator switch (manual transaxle), and the speed control deactivator switch (part of the stoplamp switch). The steering wheel mounted switches are hardwired to the PCM through the clockspring.
The speed control functions include:
  • turning the speed control system on.
  • setting and maintaining the desired vehicle speed.
  • accelerating the vehicle speed.
  • decelerating the vehicle speed.
  • turning the vehicle speed control system off.
  • canceling the speed control.
  • Do you know what DTC'S - diagnostic trouble codes are ?
  • Powertrain Control Module (PCM) Diagnostic Trouble Code (DTC) Index DTCs Description Source Action P0500 Vehicle Speed Error PCM REFER to the Powertrain Control/Emissions Diagnosis (PC/ED) manual. P0579 Cruise Control Multifunction Input A Circuit Range/Performance PCM Go To Pinpoint Test C . P0581 Cruise Control Multifunction Circuit High PCM Go To Pinpoint Test C . P0833 Clutch Pedal Switch B Circuit PCM Go To Pinpoint Test D . P1572 Brake Pedal Switch Circuit PCM Go To Pinpoint Test B . P1703 Brake Switch Out of Self-Test Range PCM Go To Pinpoint Test B . All other DTCs - PCM REFER to the Powertrain Control/Emissions Diagnosis (PC/ED) manual to continue diagnosis. Symptom Chart
    Symptom Chart Condition Possible Sources Action
    • The speed control is inoperative
    • Stoplamp switch
    • Clutch pedal position (CPP) switch
    • Speed control switch
    • Digital transmission range (TR) sensor
    • Vehicle speed signal
    • Powertrain control module (PCM)
    • Go To Pinpoint Test A .

Jul 24, 2017 | Mercury Cars & Trucks

1 Answer

Why my Suzuki sx4 ac compressor not working?

manual A/C system or the fully auto system? option?

lots and lots of reasons, i can list them all , im the electric guy.
08 SX4 , (USA spec car)
answer 1: get it serviced? not an options? do say? we cant guess
what your question is, why, ? see #1 below for users DIY.
so is the compressor dead , on engine.

  1. a/c fuses blown to any A/C device, includes blower, in heater.
  2. A/C relays bad.
  3. High/low pressure switch tripped open (loop issues (Freon(tm)
  4. AC amp (logic box) sees errors, on any of 6 inputs.
  5. they all worked before, all cars, but not now for cause.
now the step 4 elaborations..
the AMP cuts the compressor fan and clutch for many reasons,
most not for your cause. but is important all.
why,. because those wires there can fail, or even fall off.
on the 2008 the AMP is now BCM/PCM/HVAC control module
the first step is after fuse checking is the do a full OBD2 one
SCAN on the PCM port. see if there are DTC errors. (do that now)
logic fails. BCM controls the front fan (cond) or PCM does on manual AC option.
  • blower voltage dead. (Blow logic failed)
  • engine overheated (or sensor lies) "wires fell off?"
  • engine overloaded, a/c cuts at crank, and wide open throttle.
  • hi/lo switch cuts out, protecting loop from DAMAGE.
  • lots of sensors can fail here, scan it?
  • outside air temp, too cold to run A/C? (auto system)
  • evap core icing up sensor, shows too cold, near 32f.
  • The manual system uses PCM to operated the 2 main AC relays as a slave to the AC brain box. but is BCM on fancy auto system.
  • not scanning the PCM/BCM now, you will FAIL.
The manual system is below. seen in the FSM book.
the tests are easy do you want me to gue$$ or TEST.


Feb 28, 2015 | 2008 Suzuki SX4

1 Answer

Is there a test for the pcm?

no, there is no single tests. not in the least.

the hardest question on earth.
is really how to test a very complex computer.
i guess you dont own a scan tool ?
if you did you'd not need to ask this.
ill answer this is 3 classes, (my bailiwick)
  1. the car runs perfectly , full MPG and no CEL lamp and passes smog.
  2. and no DTC errors in memory or while running.
  3. it works.
  1. the CEL lamp glows key on, if not fix that first (fuse)
  2. The scan tool works, plugged in, if not fix that next (fuses)
  3. same as above owners class, if not? he, checks for DTC errors. and works those to there logical conclusions...
  4. He checks that all PCM inputs called sensors read right. (looking)
  5. he check that the injectors dont leak, or are dead.
  6. he makes sure the PCM runs in closed loop at idle, and light flat cruise, if not , we fix that.
  7. is the ECT reading, right, 180F+ or wrong, if wrong the thermostat is borked. or missing or. other reasons, the tests are easy. ask.
  8. we last check fuel trim, LTFT , long term fuel trim to see if the TRIM is centered. near 0 to +5% if not we find the cause.
  9. lots more , ill stop. fingers tired.

Pro test lab: like Cardone.
they use major ATE test equipment to test the PCM
and under stress !
click the engine control link here.

tell me ? why not just work the symptoms.
got symptoms? why not post them.?
ask for help on how to do the tests.?
why not do a full scan if the PCM using any OBD2 scan tool
(USA answers, always) you never said.

Oct 01, 2014 | 1997 Jeep Wrangler

1 Answer

Hey there I have a 2001 jeep grand Cherokee 4.7L the #8 individual ignition coil burns up with in 2 minutes. I did some testing and found that it is receiving full ground contact from the pcm/ecm even with...

The COP (coil on plug) ignition system is what is used on most modern engines. There is an individual coil for each cylinder that is controlled by the PCM (powertrain control module). It eliminates the need for spark plug wires by putting the coil right above the sparkplug. Two wires are dedicated to each coil. One is a battery feed usually from the power distribution center. The other wire is the coil driver circuit from the PCM. The PCM grounds/ungrounds this circuit to activate or deactivate the coil. The coil driver circuit is monitored by the PCM for faults If an open or a short is detected in the driver circuit for coil #8, a P0358 may set. Also, depending on the vehicle, the PCM may also shut down the fuel injector to the cylinder also. Symptoms Symptoms of a P0358 DTC may include: MIL (Malfunction indicator lamp) illumination Engine misfire may be present or intermittent Causes Potential causes of a P0358 code include: Short to voltage or ground on COP driver circuit Open on COP driver circuit Loose connection at coil or broken connector locks Bad Coil (COP) Faulty Powertrain Control Module Possible Solutions Is the engine misfiring presently? If not, the problem is likely intermittent. Try wiggle testing the wiring at the #8 coil and along the wiring harness to the PCM. If manipulating the wiring causes the misfire to surface, repair the wiring problem. Check for poor connection at the coil connector. Verify the harness isn't misrouted or chafing on anything. Repair as necessary If the engine is misfiring presently, stop the engine and disconnect the #8 coil wiring connector. Then start the engine and check for a driver signal to the #8 coil. Using a scope will give you a visual pattern to observe, but since most people don't have access to one there's an easier way. Use a Voltmeter in AC Hertz scale and see if there's a Hz reading of between 5 and 20 or so that indicates the driver is working. If there is a Hertz signal, then replace the #8 ignition coil. It's likely bad. If you don't detect any frequency signal from the PCM on the ignition coil driver circuit indicating the PCM is grounding/ungrounding the circuit (or there is no visible pattern on the scope if you have one) then leave the coil disconnected and check for DC voltage on the driver circuit at the ignition coil connector. If there is any significant voltage on that wire then there is a short to voltage somewhere. Find the short and repair it. If there is no voltage on the driver circuit, then turn the ignition off. Disconnect the PCM connector and check the continuity of the driver between the PCM and the coil. If there is no continuity repair the open or short to ground in the circuit. If continuity is present, then check for resistance between ground and the ignition coil connector. There should be infinite resistance. If there isn't, repair the short to ground in the coil driver circuit NOTE: If the ignition coil driver signal wire is not open or shorted to voltage or ground and there is no trigger signal to the coil then suspect a faulty PCM coil driver. Also keep in mind that if the PCM driver is at fault, there may be a wiring problem that caused the PCM failure. It's a good idea to do the above check after PCM replacement to verify there won't be a repeat failure. If you find that the engine isn't misfiring, the coil is being triggered properly but P0358 is continually being reset, there is the possibility that the PCM coil monitoring system may be faulty.

Nov 09, 2013 | Cars & Trucks

2 Answers

Engine cooling fan only works when ac or defrost is on

if engine at long stand still,the engine temperature will rise about 190 degrees the cooling fan suppose to automaticaly turn on when coolant temperature sensor get hot it cause its resistance decrease causing pcm to send power to coolant fan relays and cooling fans, when you turn on AC the cooling fans suppose to turn on to cool down AC CONDENSOR, IF NOT AC WONT WORK COOLING FAN COOLS DOWN REFRIGERANT SO IT CAN RECYCLE THROUGH THE SYSTEM AGAIN.your cooling is suppose to turn on when engine at a sit still if vechicle not moving as coolant temperature rises at a set point the cooling fans will turn on cool down engine.cooling fans dont turn on when you first cold stsrt vechicle unless you have AC SWITCH ON.if cooling fans dont turn on when vechicle at a long stand still or moving along slow traffic.if coolant temperature sensor been replaced and fuses and relays okay have dealership check see if pcm driver circuit working faulty pcm will cause cooling fans not to turn on.

Sep 27, 2012 | 1996 Buick Century

2 Answers

My durangos air conditioner is blowing hot even though the freon levels are right. I was wondering where the air conditioner condenser was located so I could see if it is stopped up. Not the one in front...

I think the problem that u have is the ac heater vent door broken or the motor stopped working. Very commun problem in dodge. U need to remove the dash board and ac heater box....

Sep 03, 2011 | 2000 Dodge Durango

2 Answers

Ac and heater not working. New Heater core and

You need to but a scanner on the computer and activate the AC. If it does not activate you may have a bad PCM. Also if the pressure in the AC is low it will not run. Also you have a AC relay in the engine fuse box.

Now for the bummer part. I have this same truck. Replaced heater core and I didnt get the blend door quite on track and it jammed. I had to take the dash off again. Also your center heat control may be bad.

I don't think these two problems are related. Even without AC your heat should work. Do you have rear climate control also. See if that works. If it does you may have a jammed door for the dash area

Aug 10, 2009 | 1998 Ford Expedition

1 Answer

2001 Dodge Dakota Engine Light

below is coped directly from Chrysler. sorry but if you have that code you need a PCM



1 NOTE: This DTC indicates an internal PCM problem.
If there are no possible causes remaining, view repair.

Replace and program the Powertrain Control Module in accordance
with the Service Information.


Mar 25, 2009 | 2001 Dodge Dakota

1 Answer

Diagnostic code


This symptom is diagnosed using the test P0600-PCM FAILURE SPI COMMUNICATIONS.

Ignition key ON.

Internal checksum for software failed, does not match calculated value.

  • PCM internal or SPI

Jan 16, 2009 | 2001 Dodge Stratus

Not finding what you are looking for?
1998 Chevrolet K1500 Logo

254 people viewed this question

Ask a Question

Usually answered in minutes!

Top Chevrolet Experts


Level 3 Expert

77186 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22265 Answers

Ronny Bennett Sr.
Ronny Bennett Sr.

Level 3 Expert

6927 Answers

Are you a Chevrolet Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides