VERY CONFUSED 95 GMC 6.5 TURBO DIESEL
 

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hey guys,
anyone know if a 95 gmc 6.5 turbo diesel has a ecm? and if so where is it located?
every time one of these codes pop up. it shuts of the egr solenoids.

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now can the ecm be bad or the chip inside ecm be bad?or am i looking up the wrong area for these codes to be popping up?

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found the ecm in behind glove box.dont know how to get out .another question.took egr out .now i tried creating vacumme by sucking on it.should that plunger move freely? I know its spring loaded,i dont get any movement on it until i press on it then the vacumme works a little.

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there is a fairly new vac pump on the truck.But they are known to go.It does have vac.I just dont have a guage to read vac pressure.and I know pretty much with these three codes its all vac related or electrical trying to figure out what path to go.

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well broke down got a vac gauge.reading about 20 to 22 it bounces around a bit.now some how on the way home got a 29 code glow plug relay circuit fault .im about ready to beat this truck with a sledge patiance is wearing thin.i was told to use test light wire on pos of battery and put on the glow plug terminal should light up if good.well they are fine .if this is the rite way .also when turn key on normally you will hear a click along with buzzer.i usually wait for buzzer to stop and then i start it. there is no click after a few seconds .it will start but engine still warm.IS THERE A RELAY AND WHERE IS IT LOCATED?

You say you are getting codes what are they it would help to know what they are

started out with code 33 egr control pressure/baro sensor circuit high (low vac) checked all vac lines no leaks.then code 32 exhaust gas recirclution (EGR) curcuit and code 78 wastegatesolenoid fault
now code 29 glow plug relay circuit fault and code 44 egr pulse width error

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oh and glow plugs still not responding.and unable to reset codes .how do you test a glow plug relay?

Is the WTS coming on at all??if not then it's probally bad,have you disconnected the batteries for 10 minutes yet? that will reset

sorry dont know all abbreveations what is WTS? yes i disconnected batteries for about 15- 20 min

WTS=wait to start,you staill have those code safter disconecting batteries<meaning both batteries????

YES,the buzzer does work .but i was always able to hear the glow plug relay click during the WTS.AND YES BOTH BATTERIES.
i am code 44 now

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a little recap on what i have done over the weekend.might help a little

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Hello everyone,
I have had this truck for 12 yrs all stock 240,000 miles.Spent lots of cash$$$$ and a lot of busted knuckles to keep it running.
Anyway, the truck is spitting sputtering sometimes stalls mainly rite after starting up.
i suspect it being a fuel delivery problem.It does have an after market remote PMD w/heatsink on my third one figured try after market with a heatsink this time. Its about a couple years old.
IP has been replaced twice.maybe 4 yrs old. vacumme pump about 1yr old
i am trying to test the LP .had the truck running opened the pit cock no fuel came out then stalled. same with opening top of fuel filter canister.the only time i can get fuel out of these is when i am cranking the motor over. So now i get truck running again I check the voltage on the plug for the LP and only get 6 or 7 volts .My question is it should be 12 volts right? would the oil pressure switch play a part in this? Any ideas what else to check ? How about the fuel relay switch?
thanks again for anyone with the answer

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well, ran a few tests this morning.i tested wires on oil pressure switch.with key on orange wire
12v ,tan wire 7-8v lime green 0v.Now ran a splice from lime green wire with truck running
got a 7-8v reading .now went back to LP there is black wire i'm sure this must be ground and a lime green wire for power now is reading 14v what a differance from last nights reading 7-8v. I didnt think last night to check oil pressure so no reading on that. too pisted-off by then.Now also tested the fuel pump relay,

0v -o o- 0v when key on ,7v- engine running

-o o- o- 0v
^ 0v
12v key on ,14v engine running

hope you understand diagram of relay.wish i would of checked this last night.
Today truck is running fine with the exception of
code 33 = egr control pressure/baro sensor circuit high (low vac) Once service light pops on loose a bit of power.I just put in nuetral and restart truck.then ok till i get on it again.
Any idea how to fix?
same thing going on with no fuel coming out of pitcock or filter when truck running ,only when cranking motor over.

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ok? did some more wire testing and jumping tests.i ran a wire directly from battery to LP pump ran opened pitcock lots of fuel.
Next i tested the voltage on the wire that runs from the OPS to the pump, with plug not plugged into pump, key on 0v, 14v engine running. I hooked the plug back up to pump only reading 7-8v with motor running. And pump is not working.I still think that pump should kick on with key on.
next i tested the fuel pump relay again with unlpugged to fuel pump 14v .plugged in pump 7-8v
so i am going to purchase a oil pressure switch. If that aint it i will run a toggle switch. Screw it

problem was solved with replacing the oil pressure switch.so hopefully this will help someone down the road

I,m gonna say it is a bad EGR solinoid,has come unplugged, or the egr port is possibly being partially or completely blocked and I would say if the WTS light is not comming on the GP solinoid is bad or you have a bad fuse

is there a way to test the gp silonoid?checked fuse (its good)

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any way computer playing games ?curiuos
i had the egr off and did notice one of the ports were pretty caked up .so i scraped it clean.

It is a million to one shot that the computer is bad so I would say no due to the fact truck will run bad ECM=non running truck,I am not sure about a test most ppl wj=hen having GP relay trouble do a relay mod some heavy gauge wire and a heavy duty push button starter switch will do the trick I put one on a 93 6.5 worked great for 2 years till the truck was sold if you go to your local NAPA ask for a STB6301 this is what I used on the last one I did

ok placing order for egr,egr solinoids (2) and the gp relay.i let you know what i find out .thanks Mayham

Get AC DELCO parts trust me on this I know they cost more but there is a reason

i agree but having trouble locating an auto store that carries ac delco parts.any idea's?

The big 3 can get AC parts they may have to order them if not get napa parts as a second choice

ok, instead of ordering everything i picked up a new gp relay.sorry but (standard) brand I found out anyway that mine might have been good. there is a short in a wire i think in the cluster behind the fuel filter not sure yet kinda straightened them out somewhat. kept blowing engine fuse (20a) so far no fuse blown.
lastnight i kept looking at glow plug fuse.
it runs now. So now i can do other tests on egr system.Still getting code 33 = egr control pressure/baro sensor circuit high (low vac) after putting the pedal to the floor on test drive. with in that noticed oil pressure really low engine and engine spitting and sputtering at an idol.i checked vac to egr solinoids w/green dot has vac. Middle one no vac (I dont know what color dot missing)and of course no vac on third w/white dot closest to firewall. when I reset the computer vac works on all 3 solinoids. But still spitting and sputtering engine revs up and a nother blown engine fuse.Now i did clean the ports in the intake this morning i dont know if this may cause the spitting and sputterin. So still stumped on that .
Now, is there something else that would send a signal to shut these solinoids down or just bad solinoids? I realize I am dealing with 2 different problems.(OR MORE)

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found out why engine fuse kept blowing.A short in the heating element wires, located on the bottom of fuel filter canister.which coused the glow plug relay not to work.Once I fix that issue.I will get back on the egr solinoid crap.

To your 1st question yes there is a PCM, Powertrain Control Module behind the glovebox, with the odd codes you have glow & EGR are no way connected I suspect you are having grounding issues which your vintage vehicle not uncommon.

Passenger side rear head stud are where the gnds for PCM-Glows is must be spotlessly clean.

Site mods if you have to delete the hotlink I understand but this can be helpful to the 6.5ers here Grounds what are they & where are they

You said 4x PMDs???? where do you have yours mounted currently ? anywhere under the hood is bad ju-ju it needs to be remote mounted on a cooler plate to have any chance of surviving.

Ok order came in .New fuel warmer, which was causing the fuse to blow.(exposed wires).
put all 3 egr solinoids on and egr sensor located on firewall. So far so good no codes and running strong.and yes all ac/delco parts. I want to give thanks to MAYHEM for all info he has given.let ya know how it goes.:jump::c:

:tu: good deal diffrangle