Question about 1998 Chevrolet K1500

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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.

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  • Chevrolet Master
  • 21,949 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

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How to tell if body controll modgul is bad will not go to 4 cylender mode when warm


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Jan 07, 2016 | 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.
retired.
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.

25492229-331th0o4ygoodik5f23zyrbq-3-0.jpg

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)
owners:
  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.
mech.101:
  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.
http://www.cardone.com/tech-help/electronics


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

Symptom:

P0601-PCM INTERNAL CONTROLLER FAILURE
POSSIBLE CAUSES
POWERTRAIN CONTROL MODULE
TEST ACTION APPLICABILITY

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

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

Perform POWERTRAIN VERIFICATION TEST VER - 2.
38
COMMUNICATION

Mar 25, 2009 | 2001 Dodge Dakota

1 Answer

Diagnostic code


SYMPTOM
P0601-PCM INTERNAL CONTROLLER FAILURE

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

WHEN MONITORED
Ignition key ON.

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

POSSIBLE CAUSES
  • PCM internal or SPI

Jan 16, 2009 | 2001 Dodge Stratus

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