does it need a CPU??

[Shotuscnc]

my 95 suburban is defaulting to limp mode in the driveway now..

DTC's 17,18,19,35,36,54 and 78

new stanadyne pump
new crank sensor
new lift pump
new oil pressure switch
new filters (have a racor pre-LP)

grounds have been chased and duplicated..

all to no avail..

the replacement computer is $200... and I don't mind the investment for peace-of-mind..

any suggestions are appreciated..

[Shotuscnc]

also has remote FSD which is new... replaced the new FSD after stanadyne pump did not fix.. no help.

[ttpost]

have you checked all your connectors on the motor and in the glove box? i just went through computer problems, i think mine were caused from a new battery that shorted(about a year old diehard).
i went through 3 computers before i got a good one, all supposedly rebuilt. :mad:

if you get a new computer make sure it is a delco rebuild, dont mess around with the cheapo units. they also come with a one year warranty.

there are authorized delco dealers out there that sell them alot cheaper than gm. good luck

[Shotuscnc]

thanks TT... i have checked all connectors that seem relative... and replaced the heath chip with stock.. still problematic.. the batteries seem fine.. have removed insulation and placed big bolts for secure battery terminal connections.

i was thinking about a cpu from NAPA.. can you help me with a source for DELCO unit... i feel that will be part of final resolution... right now i just feel lost.. so much for OBD I dtc's

[Shotuscnc]

i cleared the codes... jumper A&B depress brake &throttle

still had problems but rev-tuned in the driveway for a few minutes.... it cleared up.. may have been something clogging an injector.. tho it seemed more systemic than one injector..

all diagnostics still pointed to CPU... guess i am off the hook until it reappears.

little peace-of-mind for the next few weeks.

[ttpost]

doesnt soud like a computer to me, but if you decide you need one i will gladly put you in touch with my local dealer, if i remember right mine was 170.00, they have great prices. you or anyone else can email me @ townsenstrading@aol.com . i will talk to them and see if they will ship directly to you, if not i can pick one up and send it to you. let me know if you need one.

[damork]

It can be a headache but I ended up installing a GM rebuilt CPU during one of the pump installs. I'm not sure if it was a culprit but some say the 94-95 models had some bad units in them that led to problems with the pump controls. So far mine has worked much better, but who knows what fixed it - wires, pump, lift pump, grounds, filters, FSDs, you name it I've changed them all.

Going to a dealer is expensive and so is changing parts. I do my best to follow a logical troubleshooting method making one change at a time and observing the results. Owning a 6.5 has been one of the biggest challenges in following such a procedure, as the rules seem to change about the time you think you have something fixed.

Sometimes I think the best thing I ever did was install the DSG gears, as all seems to work much much better since I did that, and timing is everything with these trucks.

[Shotuscnc]

thanks TT... I would like to get a PCM as it will provide some peace-of-mind.. at least to have it with me..

I will email your dealer..

have a good and long weekend

[Shotuscnc]

Damork, I can appreciate your feelings as the worst is not knowing what fixed it... or even if it is fixed..

I believe that my crank sensor may have been at the root of the problem all along...

I have also come to trust my own instincts(and those of the GM manual)more than the paid professionals..

now I understand when I hear 'the injection pump is commonly mis-diagnosed'..

esp. when the electronic systems can be upset/reset fairly easily by ground faults..

the problem can temporarily disappear with the $1500 'repair'

[ttpost]

hey i misled you on the last post, it is not a gm dealer but a local parts distributor that can get gm parts, it is cost less auto parts in vancouver wa. the phone # is 360-254-5710 sorry about that.

[Marty Lau]

PCM (ECM or computer) GM# 16212488 (for 1995)
Dealer list $293.11 GMPartsDirect $175.87 with shipping, local AC Delco Dist. $178.84 (G&M Pam Oil co) Now there is a $200 core as these are GM "remanufactured".

NAPA $114.95 plus $78 core

[ttpost]

the napa computers are what i had. went through 3 of them all bad with different problems. from what i have learned they buy them from a supposed rebuilder.

the next thing i learned is that the supposed rebuilders just buy them from the wrecking yards and stick tags on them.

what is more interesting is that the wrecking yards sell computers and require cores, which i assume they sell to the rebuilders. vicious circle.

anyway i like the one year warranty good luck

[tom.mcinerney]

Chris--You may well be due for a PCM . All the power to the sensitive electronics has to pass thru a set of points in the ignition switch. If you're still running the original, may as well refit that too.
I'm not real sharp on the DTCs, you seem to have a lot of pump-related codes. It may be worth checking lift pump pressure (at front-engine drain), and assuring that there are no streams of bubbles in the fuel...
A final note [and i repeat, a new CPU is a good notion at this point] is that a couple folks have noted abrasion on FIP harness wires, and some FSD connector issues. Specifically, there's a harness filter {looks like wires enter/exit a molded-rubber block a couple inches long, by nearly , say, 5/8" square cross section}.This thing beneath InManifold, draped over FIP. One member eliminated his, another cut/spliced a leg that lost continuity. Mine had insulation worn thru, but only by plastic wireloom, OK.
A few people have reported a ground near PCM, apparently an eyelet, that was a problem. (I've yet to spy this one).
Good Luck, hopefully the Crank Position Sensor did it.

[Shotuscnc]

Tom Mac... you nailed it...

after pulling tank to remove sock, another round of filter changes, bigger ground cables, a new battery.. I read your post..

let it idle and pulled on the pump looms.. dead.. pulled the upper intake,

the electric connector plug to top of inj.pump seemed too loose.. I discovered that I could remove the short harness extension with rubber parallel insulator in entirely..

works like a charm.. and the connectors are snug.

thanks for being an active member of the board.

I had ordered a CPU this morning.. and just cancelled it.

Chris