# 1995 chevy van g20 4.3l



## lostinautohell (Aug 22, 2010)

recently light began to pop on intermittently. obd1 code was 14 for a coolant temp circuit issue. i changed both the temp switch and the temp sensor, the connector, as well as putting in another temp sensor becnsse i was told its possible i might have gotten a defect sensor. the wiring looks good though i havent ruled out replacing the whole wiring all together. ive been told it could be egr, map, or o2 sensor. this is what is happening ( the van will drive fine then after about 15 driving the light pops on and it bogs. after the light goes off the bogging stops. the light maintains code 14 issue (yes i reset the code with changes by disconnecting neg cable to battery) however when i unplug the connector to the temp sensor the van runs fine ( hence is why i replaced the new sensor with a new sensor cause i was told the sensor though new may have been bad still) but i doubt it happens two times in a row. sorta lost here and before i go rewiring or replacing ecm/pcm would be happy for any feedback on this


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## Wrench97 (May 10, 2008)

Is the temp reaching 190 degrees, a thermostat stuck open can cause it to run too cool, setting the code, it bogs because once the fault is detected it goes into what is know as "Limp home mode" where a preset program controls the spark and fuel settings just to keep it running.


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## lostinautohell (Aug 22, 2010)

i was going to check the tthermastat but someone said it wasnt part of the code 14 issue. but i was assuming to check that. would that explain why the van runs fine with the temp sesnor not plagged in cause the cooling fans are running all the time then?


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## Wrench97 (May 10, 2008)

Yep that could explain it.


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## lostinautohell (Aug 22, 2010)

itll still have issues if the thermastat is bad even though the gauge doesnt show really hot right. cause the gauge sits just inbetween (which before changing the temp switch it didnt work at all). i just want to make sure im getting it right

car runs good cold
then light is thown on and bogs after its warmed up driving about 15 minutes or so
the temp gauge doesnt show signs of spiking hot but yet the vehicle runs fine with the temp sensor disconnected
everything done so far include changing out the temp sensor 2x, the temp switch, putting on a new connector, the wiring looks great plus the continuity test shows no short. 
and yes i do reset the code by disabling the neg cable to battery

i have to wait for engine to cool down until ii check the stat and im hoping this is the cause nothing else seems to be explaining it other then just rerunning new wires and lastly a new pcm. 


i am such a nerd.....


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## Wrench97 (May 10, 2008)

Stuck open would make it run too cool not too hot, the ECM is programed to meter the fuel at the correct temp if the engine does not reach that temp it sets the check engine light, this is a emissions system setup too cold produces more emissions hence the fault light.

Some of the older setups(pretty sure it ended in the 1980's) had a problem with the temp sensor leaking and the coolant wicked through the wire into the ecm causing damage. You could tell by unplugging the connector at the ECM and looking for either green antifreeze or stains from it.


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## lostinautohell (Aug 22, 2010)

so far changed the thermostat
temp sensor
temp switch
new connectors
but the light still pops on reading obd code 14
next step i will run new wiring from the connector to the ecm/pcm and if no change them then i wil just break down and cry.....lol....not
then i will just change out the ecm/pcm for another. 

if it still gives me code after going through the whole diagnostic correcting the coolant temp circuit then im really lost but one good thing is i am learning while doing this.


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## lostinautohell (Aug 22, 2010)

could it be the o2 sensor though may i ask? if that fails it can still run but maybe throwing the obd 1 code 14 cause its not reaching it op temperature. i havent checked that yet but imma also look into that, the fan then rewire coolant circuit then finally ecm/pcm


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## Wrench97 (May 10, 2008)

The O2 sensor should give you a O2 sensor code.


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## lostinautohell (Aug 22, 2010)

i tested the volt to the yellow wire on the temp sensor connector and i get a little under 4. to 4.6 volts which i am sure its suppose to be around 5. imma test again cause not sure if its faulty tester or bad connection with test leads but if the voltage is under what its suppose to be that i guess should suggest a short to the ground or bad ecm


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## lostinautohell (Aug 22, 2010)

this is what i get and tested 2x i believe digital reader cause analog is like the radiation detectors i believe...lol

with key on i tested
yellow=5.8v
black=34.2v

yellow= 0.0 ohm
black= .190 ohm

with the key off i read

yellow=.5v
black=0.0v

yellow=4.45 ohm
black=1.2 ohm


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## Wrench97 (May 10, 2008)

Your scale is off I think, sensor voltage is usually .5v, and there is no way you had 34.2v in a 12v system.


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## lostinautohell (Aug 22, 2010)

i had the meter set on the dcv setting i was told that was the correct setting to put it 
the meter i have has on the right side selections for 
dcv
acv
ohm or the image of the omega sign
ACmA
diode testing
then continuity testing

on the left side of the meter 
is battery load test with 1.5, 6, 9, and 12volts
DCmA
dc10a


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## Wrench97 (May 10, 2008)

That's a digital meter, the scale would apply to analog meters(the kind with a needle and you have pick which scale to read on the face)

For the 34v reading did it say 34.2 mv for millivolt?


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## lostinautohell (Aug 22, 2010)

apologies yes it says mv so its reading 34.2mv on the black/ground wire


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## lostinautohell (Aug 22, 2010)

also these were the cold readings


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## Wrench97 (May 10, 2008)

That's just residual voltage, you can measure across you fingers and get that

The ohm readings across the yellow and black won't tell you much other then it's not open(cut wire) and not shorted (00 reading) to ground or each other.

You've done the simple test you can do with the code readers, you need to get it put on a better scan tool that allows you to see what the temp reading is and what commands and responses are being sent to and from the ECM. 

Bad grounds will generally set multiple codes as the ground will effect more then a single sensor. 


One other thing some of those have 2 temp sensors, one works the gauge or light on the dash, the other is the coolant sensor for the ECM, are you sure you changed the correct one?
Temp switch> http://www.autozone.com/autozone/pa...f?counter=0&itemIdentifier=19146_77401_15459_

Temp Sensor> http://www.autozone.com/autozone/pa...vpZ9gslt?counter=0&itemIdentifier=146258_0_0_


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## lostinautohell (Aug 22, 2010)

yeah i changed both which found out the the temp sensor switch needed changing anyway and also changed the coolant temp sensor 2 times cause was told though i bought it new doesnt mean the part wasnt defect from manufacturer and since it had replacement warranty went ahead and tried the second one but still had same issue so i returned the part back.

i have a really good feeling though the fault lies in the wiring or connection though visibly the wiring looks okay. it wont take much work to rerun new connection from the sensor to the ecm the wiring is fairly easy to access. then at that point if issue still at hand then ill try out another meter reading with another scan reading. i really thank you for your help though so far this has been the most useful information i received. was hoping the meter tool i purchased was more helpful. 

i want to do temp reading but the engine gets warm so i want to resort to that toward the evening when ill come in and relax and let the engine cool down overnight. 
again really thank you ill be posting back after i rewire and drive for any results of change


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## Wrench97 (May 10, 2008)

Use the ohm meter to check the wires, unplug from the ECM and locate the yellow and black wires, from the sensor side terminal end to the ECM connector terminal end should be close to 0 then do the same for the black, do not pierce the covering of the wire measure from inside the connectors, use paper clips if the meters probes are too large.


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## lostinautohell (Aug 22, 2010)

well i attach new wiring to the connector but the ecm/pcm has one red connector and a blue connector. i have the haynes manual for this vehicle but what sucks is its not very informative.


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## Wrench97 (May 10, 2008)

No they don't have the wiring diagrams.
You'll have to trace it back to the harness to the connector and go by wire color. The ohm meter will tell you if you have the correct wire, Disconnect the battery when playing with these connectors/harnesses.


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## lostinautohell (Aug 22, 2010)

well i rewiredthen cleared old code and then drive and the code came back with the bogging issue only when light cam on. i figured id please the higher then though brother in laws father by clearing code and disconnecting the o2 sensor just to see if the o2 sensor was the issue but lol proving him wrong the issue was still there and then showed that now instead of obd1 code 14 i know got both the 13 and 14 code. so the van ran like crap when he suggested egr, and the map sensor and now the o2 sensor so his info is dead in the water. the only time it runs fine si when i disconnect the temp sensor connector. and since i reran new wiring to be sure there wasnt a short in wire i can now assume is just may be the computer(ecm)


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## Wrench97 (May 10, 2008)

I would only condemn the ECU after checking with a scan tool that will show you what temp the sensor is reading.


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## lostinautohell (Aug 22, 2010)

now the switch just controls the gauge so that wouldnt have a temp issue but if the actual col temp sensor is reading high temps then what other cuase could it be there isnt much to that circuit besides the two sensors the wiring harness and the ecm.


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## Wrench97 (May 10, 2008)

Normally this code is set because the temp is too cold, the engine is not reaching proper operating temp to meet the emission standards(that's what most of the electronics is for to meet the standards, better fuel mileage was a secondary benefit with OBD systems).


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## lostinautohell (Aug 22, 2010)

i could just skip the rest of the work and just unplugg the coolant temp sensor and drive it around and just monitor the fluid. just not understanding what else could be causing the issue. so far just looks like the brains is feeding the wrong info to the sensors since the veins and the organs were already replaced


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## lostinautohell (Aug 22, 2010)

question (i know im a pest) but if the vehicle is cold the fans dont kick on right until it reaches op temp and requires them to come on. so if the van is temp is cold and i start it the fans should not be on but if i start it and they kick on right away then there maybe a fault in the fans keeping things cool and causing the temp sensor to read cold right?


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## lostinautohell (Aug 22, 2010)

nm the fan is connected to the moter lol it will be on cause thats connected to the belts that will turn them...lol


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## Wrench97 (May 10, 2008)

Yea I didn't think it had a electric fan setup.


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## lostinautohell (Aug 22, 2010)

well i dont mind throwing an ecm at it at this point it doesnt cost to much will be like 80 bucks after core. i know most come to avoid paying to much or going to a a professional shop but i love projects and it has been a learning experience. ive never really worked on a vehicle before and basically i want to get a basic understanding of the locations and what things do. (as well as eventually fixing this problem) i did check the map sensor, the egr valve, the o2 sensor those all seem good i havent checked the throttle sensor but i dont think that will set code 14 i think there is couple other codes for that. before i decide to rewire the original harness back i am going to attach the new ecm to the external wire i ran just to be sure to rule out wire harness short after that if the code pops im lost cause there is nothing left to check that is within that circuit


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## lostinautohell (Aug 22, 2010)

okay you said there are two temp sensor one for guage and one as the sensor. the guage would not be causing issues with the wiring would it? cause thats just the guage control. i have only reran wiring for the coolant sensor itself. was just wondering if the sensor switch would also cause the issue with the code 14


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## Wrench97 (May 10, 2008)

No the gauge wire will not cause a ECM fault code.


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## lostinautohell (Aug 22, 2010)

fixxed so far. new ecm and drove it all over today twice and no code and no bog. not discrediting the waste of other parts as a few were really needed anyway. thank you much it has been very helpful and learned quite a few things. now on to the pitman arm


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## Wrench97 (May 10, 2008)

Good to hear that resolved it


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## lostinautohell (Aug 22, 2010)

yeah resolved but was presented another issue when i drove.... the water pump broke. what im wondering is some say when a fan clutch is bad its good to check the water pump . is it good to do the same if your changing the water pump to change the fan clutch. i couldnt do a wobble test or spin test on it cause the water pump busting makes the fan assembly wobble anyway. and now its all out and i would hate to stick a new pump in if the fan clutch is bad. is there a way to tell its bad when its not assemble in the vehicle


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## Wrench97 (May 10, 2008)

The best way of course is on the truck, but look for any signs of oil leakage from the fan they use oil to drive both the torque and temp controlled type fans, play in the shaft or oil leakage from the seal would it to fail.


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## lostinautohell (Aug 22, 2010)

well fixed the water pump, no leaks fan clutch and its all good. however now the engine light comes on for obd code 43. i looked over the knock sensor and it looks good connection wise. i do here which i didnt before the water pump blew a knocking. will it eventually kick itself out or did the water pump cause knock sensor issues and also my temp gauge stopped working after i replaced the coolant temp switch .....ugh this van i love it but its making such a headache


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## Wrench97 (May 10, 2008)

The water pump probably didn't cause the code, Clear it and see if it comes back, check the wiring at the plug on temp sending unit.


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## lostinautohell (Aug 22, 2010)

i did check the temp sendor and i noticed the wire needed fixing but the guage still doesnt run this after i just put the new sendor switch last week. 

i cleared the code but it came back. there is a knock in the engine (thus occurring after the water pump blew) but the code is 43 for the Knock sensor this code was not present prior to the water pump blowing and the knock occurring. when i found what i think is the knock sensor. (located right above the temp sensor switch) i also notice the same looking sensor on the other side of the engine. is there 2 kknock sensors for this model. and changing them would that reduce the knocking in the engine


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## Wrench97 (May 10, 2008)

The knock sensor detects pings so the ECM can adjust the timing, it should be located on the side of the block in the center of the engine below the exhaust manifold usually on the right side. If it's a knock rather then a ping it may be detecting the knock and since the ECM can't tune it out is throwing the code.

How hot did the engine get when the pump went?


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## lostinautohell (Aug 22, 2010)

im assuming pretty hot. it sounds like someone chopping veggies really fast the knocking and not like hail on tin like a ping. strange is it runs fine except knocking after water pump failed and the new code. the temp sensor switch for the gauge didnt show any signs of hot it showed normal but since the pump blew the temp gauge stopped working


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## Wrench97 (May 10, 2008)

That sounds like the valve lifters may have pumped down have you checked the oil to make sure there is not any coolant in it?


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## wally246 (Aug 4, 2006)

How might one test a coolant temp sensor on a chev S-10 4.3 2-whl drive
? I have a thread going with Octane but your input is welcome also. Thanks.


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## kjms1 (Jun 4, 2010)

dont think there is a prob with the wiring ... if there was it would be there all the time NOT just after it warms up

first thing is you need to get the true coolant temp


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## wally246 (Aug 4, 2006)

kjms1 said:


> dont think there is a prob with the wiring ... if there was it would be there all the time NOT just after it warms up
> 
> first thing is you need to get the true coolant temp


I called Autozone to see if they had some kind of thermometer to check the coolant temp and they said they didn't > there is one more place I can check.


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## kjms1 (Jun 4, 2010)

the best way is with a scanner hooked to the ECM and look at the coolant temp or remove the temp sensor and hook up a mechanical gauge


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## wally246 (Aug 4, 2006)

kjms1 said:


> the best way is with a scanner hooked to the ECM and look at the coolant temp or remove the temp sensor and hook up a mechanical gauge


We managed to find a thermometer. What would be the average temperature variation between the block temp and the temp at the fill mouth of the radiator. The vehicle is not moving and has a mechanical fan. Thermostat obviously to start and then heater control valve/switch. I just know the heater is not putting out the right amount of heat. I am trying to convince my friend that I am right and he is hardheaded and ignant!:upset::4-thatsba1994 chev S-10 4.3 V-6


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## Wrench97 (May 10, 2008)

It'll vary with cooling system design and efficiency, but after the thermostat opens it should be close to 190 for 195 degree stat.

Make sure you have all the air out of the system and the coolant is circulating through the radiator. Also check for air bubbles in the radiator while it's running.


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## wally246 (Aug 4, 2006)

*Re: 1994 S-10 4.3 V 6*



wrench97 said:


> It'll vary with cooling system design and efficiency, but after the thermostat opens it should be close to 190 for 195 degree stat.
> 
> Make sure you have all the air out of the system and the coolant is circulating through the radiator. Also check for air bubbles in the radiator while it's running.


 I read somewhere that there is a cooling system bleeder for this vehicle but so far, I have yet to find a diagram for this system and for the hydraulic clutch. If you have a site, I sure would like to have it. Thank you.


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