i have a 94 s-10 blazer cmfi vin w 4.3l (single injector) i have 12v from injector plug red wire to chasis ground and to signal ground (blue)but i get a l.e.d. light to light dimly but no pulse durring crank.(keep in mind crossing the injector plug is dim and going from 12v bat. to signal ground on injector plug is dim, but going from red wire on the injector plug to chasis ground is brite) i have checked the signal ground (blue) circuit with continuity its ok. with computer disconected i put 12v through the blue wire(injector plug) and checked at the computer plug with a regular test light and led light were ok.with computer connected all test point to the pcm malfuntioning. i had a extra pcm,but achieved same results.there is now way i can test the pcm here but do you think i have another bad one or just missing something?car will not run. i have fuel pressure @ 60 lbs and does not bleed off but 5 lbs after 1 hour pressure wouldnt be the problem.i have jumped the injector and it fires all six poppets and drops to 45 lbs from what i have read this is a correct drop. but if you plug the injector connector in it will not fire injectors with k.o.e.o. nor with cranking. another question i have what tells the pcm to fire the injector? according to my hanes manual 24071 it has the EDI system and in 5-2 under EDI it says the camshaft sensor is to detect camshaft position and sends this info to the pcm . the sole purpose of the camshaft position sensor is to provide the pcm with info for any misfire trouble codes. in the event of failure or damage the camshaft sensor is not directly involved with driveability. it doesnt have a crankshaft sensor, so what controls it. i no the computer compiles info from the tps map cts and iac to calculate the pulse width of the injector. i appriciate your time and knowledge, please respond.

 

have you checked for spark? have you checked the distributor? the 94 and older distributors are notorious for the magnets cracking inside the center of them....

 

My manual says the pulse width is controlled by the "control module" which I believe is the PCM. My factory wiring diagram shows no red wire to the injector. It shows a pink wire with black stripe running from the ECM 1 fuse in the fuse block to Connector C103 Pin A on the injector. The Dark Blue wire runs from Pin B on the injector then runs to the PCM at Connector C211, Pin A16 which is identified as "Fuel Injector Control" and cycles to ground completing the circuit and energizung the fuel injector. I'll have to double check my 94 Blazer about the wire color discrepancy. I would think that if you have power to the Pink/Black wire at the injector at Pin A and grounded the Dark Blue wire (disconnected from the PCM) you could tell if your injector was working (appears to be basically a relay and you could probably hear it energize). I don't think putting 12v to the Dark Blue wire was the way to go because it hooks to ground inside the PCM. At least that's how I'm reading it. I don't have a detailed breakdown on the inner workings of the PCM but am sure it gets input from several sources. Let us know how you made out. I'll keep looking too.

 

yes i have spark @ plugs.mind you that the injectors are not firing.yes pulse width is controlled via pcm but varies acording to info from various sensors. it also needs to be told win to open, the other(pulse width)is just how long to be open. as far as the red verses pink wire, it is pink with black stripe @ the check point by the oil fill tube,then just red to the injector(thank you for pointing that out) i did put 12v through the blue wire through the injector plug via led test lite. and 12v via bat. through led test lite. this is the same way a void lite does. both ways were both dim but still registers 12v with digital multimeter. if you hook the led test lite from the fuse block (red?pink&black) wire to chasis ground or bat ground it preforms brightly. i also unhooked pcm and put 12v bat power through injector plug via blue wire and checked the pin of the pcm plug with the test lite it preforms brightly i think this should tell me that the blue wire (ground circuit for pcm injector pulse)circuit is preforming correctly.this should not hurt anything since the pcm is unplugged and is just a wire circuit nothing else inline. in my hanes book one section doesnt show a crank sensor( witch i have recently found to be part of the inj. fire) in the injection circuit , but in the description for the ignition system(witch shows it to have a edi system) it says there is one on the front of the motor by the fly wheel.(will see tommorrow and test) but it does not say it has any dirrect relation to its runability?(please respond to that statement) i did however find that ther is a cam shaft sensor, (it is in the distributor under cap) there again the book says it has no effect on its runability(it states if the camshaft sensor was faulty it would run rough or missfire, mine will not run.)if any body has a diagram of the pcm plug in detail please let me know? i appriciate your intrest with this thread. please drill me with any ?s you may have since as you see there may be a descrepincy in my info.or you may see something diffrently, i want you to get the full picture of the issue as best as possible. THANK YOU!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

I have a factory manual on Driveability & Emissions and Wiring Diagrams for the entire vehicle. The "Engine Controls" diagrams are broken down into approximate subsystems all focused on the PCM with a breaksown of the PCM connectors identified by circuit name and number with corresponding socket/pin numbers on the 32 pin connectors. I really recommend you get one (not that I'm holding out on you - there's just pages and pages of Engine Controls) but they're pretty cheap [$35.00] and far superior to the Haynes or Chilton manuals. Here's the website I ordered mine from. You probably want the Service Manual too. If I did it over, I wouldn't get the Unit Repair Manual unless I was going to overhaul something. I'd scan it to you but this stuff is copywrited and don't know if it's cool (or legal) to do so. I do know it's accurate. The stuff shows up pretty quick.
http://www.helminc.com/helm/Result.a...J7586RVDTU32PE

 

hey gimpy blazer thank you for your time and info in the direction of this manual,but right now my wife and i are disabled and strapped for cash. when the cash is there i will purchase that manual(sounds better than my haynes) as for now you or anyone that can add any info to this thread please reply. to all of you and gimpy THANK YOU!!!!

 

Can give you info piles high. I am disabled too so I know wwhere yiu're coming from.

 

gimpy blazer could you at least tell me what wire is the pcm 12v supply color, and pin location, also the main ground for the pcm color, and pin location? being challenged with your body is no laughing matter is it? sorry to hear about you bieng disabled to, i feel ya. thank you

 

There are actually more power input sources tan one. There are different fuses that suppy 12 v. On the two 32 pin connectors you have cavitoes A & B on the red one and cavities E & F on the blue one. Here's the list with wire color, cavity and description. There are some typos in the chart I got the info below from. I tried to go to the actual diagramand fix them but if you find something different, let me know,

Blk/Wht A1 System Ground
Tan/Wht A2 System Ground
Lt Blu/Wht A3 Stepper Coil A High
Ppl/Wht A4 Distributor Ref High
Blk/Red A5 Distributor Ref Low
Lt Blu/Blk A6 Stepper Coil A Low
Lt Grn/Blk A7 Stepper Coil B Low
Lt Grn/Wht A8 Stepper Coil B High
A9 Not Used
Ppl A10 O2 Sensor High (?)
A11 Not Used
Tan A12 O2 Sensor High (?)
A13 Not Used
Wht/Blk A14 Data Link Connector
Dk Blu A15 Throttle Position Sensor Pin C)
Dk Blu A16 Low Side Inj A

This is for the A cavity on the Red PCM connector. It's late. Gotta go somewhere later this AM. Will try to get the rest of the connectors laid out later today. All grounds are either Tan/Wht, Blk/Wht or Blk from what I can see.

 

gimpy blazer no need for the rest of the wires(thank you anyways)unless you would like to list for others. thurs.(yesterday)morn. i decided i would trace over my steps to see if im missing something so i decided to check for spark again. i plugged the coil refferece wires in, and put the coil to dist wire on. (note i removed coil to take upper manifold off)instead of diconnecting again i laid it to the side. i decided to check for injector signal again at the plug beside the oil inlet tube. GOOD NEWS!!! i now have signal. DDOOP connecting the coil wires (signal) completed the circuit for the injector pulse, major overlook , i over looked this in my book due to the fact that the wiring diagrams are lacking in ilustration. but seing this lets me no that the crank sensor is a major factor in runnability. but this did not solve the problem that first arrived(car stalled and would not run again,you guys did not see this in the thread in the start because i had already narrowed this problem down to pulse signal circuit just couldnt find out where). since i had signal to the connector beside oil inlet tube, i needed to check from inlet tube to the injector. once again i had 1.8 ohms through this connector which would make you think the circuit in this plug was good since this injectors resistance should be 1.33 to 1.77 ohms. so i disconnected the plug and tested each side of the plug for continuity. checked good. so i scratched my head and wondered? the injector fired when i jumped it and it has proper resistance so what could it be? so i took the plug off of the injector and tested it for signal none but every time i checked it at the connection point by the oil fill inlet it tested good(mind you that when you test the male side of the plug by the inlet tube and the injector was connected this completes the circuit through the injector) so i come to the inclusion that the injector plug when trying to draw amps through the circuit(it takes 4 amps to open and one amp to maintain open) it was losing connection. normal test would not put a draw on the circuit. in order to test this theory i jumed the female side by the inlet tube to the injector and had my brother turn engine over and WAIT FOR IT !!!! PRESTO WE HAD INJECTOR FIRE!!!!!!! so i went to auto zone for the pig tail at the injector they didnt have one for my model ven code#W, but one would work from a T.B.I. unit so i purchased it for 12.99 plus tax and i was on my way. moral of the storry is dont be so quick to judge good tests, for something else may be hidingalthough i did many of the correct test i was overlooking one major factor(coil signal wires unplugged) so dont just start replacing things for it is a lost cause, keep on testing and re-trace your steps(the answer will show itself evetually) even if you think it is right. i appriciate the help and time people give to others and myself on thes threads, because it can save alot of time and money. until the next cituation arises THANK YOU AND GOOD BY