Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
The truck will no longer crank... nothing happens when i turn the key. it only cranked when i had the connecters arked on the starter.
the SES light comes on when the ignition is ON. also when the pcm is dissconnected.
it is like the pcm isnt turning on but all the lights and whatnot have power
the scantool says "please connect to vehicle" and the tool works fine in other vehicles...
Hello my name is XXXXX XXXXX I will be more than happy to assist you.
Do you have a test light?
i'll try now...
also, why wont my scantool see my pcm? (see above ↑)
sorry for the delay.
Check and make sure the IGN C 20 Amp and IGN A 40 Amp fuse is not blown in the under hood fuse block.
Remove the Crank fuse and see if it is blown. If not put it back in and see is there is power at it when you turn the key to the start position.There are metal tabs on the fuse you can touch the test light to, to verify power.with out takeing the fuse out
Remove the Starter Relay. use the test light and test all 4 slot the relay prongs fit into for power. Do this test while holding the key to the start position. How many of the slots light the test light up?
ign on - top left (from drivers side) makes headlights come on, top right has power
ign START - above plus bottom right
So you have power at 2 of the 4 slots. Great. The headlights coming odd but helps confirm my answer.
After you put the engine back in you must have missed connecting a grond wire or did not tighten the bolt. The Starter Relay and PCM both get there ground at the same point # XXXXX in the picture below G102 and G103
If that is not the problem let me know, but it should be.
i'll check it out tomorrow...
Thanks for your help. i will thorw in a bonus for your time.
Keep in mind there is either 2 to 4 wires that ground there.
Let me know what you find and if everything is working.
those to lines are grounded correctly.
just to clarify... the starter relay pins:
key off - 1 pin has power
key on - 2 pins have power (grounding new pin make headlights come on)
key START - 3 pins have power
remaining pin is ground
Show me which pin have power. In the picture below standing at the drivers side tire looking at the starter relay. toy have pins 85, 86, 87, and 30
Which pins have power and when?
85 - pwr when ign START
86 - pwr when ign ON
87 - GROUND
30 - pwr when ign OFF
Right now disconnect you battery, you should never have power at #30 like that.
I will load up more info while you do that.
what could cause that?
Im sorry 30 Should have power at all times.
86 should not have power that is the ground side of the relay that goes to the ground on the block.
85 Should have power when cranking
87 goes to the starter.
Unhook the starter connections, connect the battery and see if keep getting power at 86.
If you do let me know because there is a ground problem and I will load up all the places there are ground wires.
either way there should not be power at 86
i'll check tomorrow...
can u send the diagram of ground wires? i'll verify those also...
Sorry for the delay on the ground locations. The # XXXXX the picture will tell you what # XXXXX ground is in the picture. Some of these grounds may not be on your vehicle.
G106 # XXXXX / G118 #5
G108 # XXXXX / G101 # XXXXX / G110 # XXXXX
G112 # XXXXX / G100 # XXXXX
G111 # XXXXX
G107 # XXXXX
G102 & G103 # XXXXX / G105 & G104 # XXXXX
Does it turn the headlights on when the ignition switch of off?
Also does it turn just the low beams on?
There has to be a ground wire off at the back of the block, not connected correctly, or the wire got cut. Normally when you turn the key on the headlights should come on, but they are not. Both the Headlight relay and starter relay have the same ground wire plus a few others componnets. When you ground #86 it is giving the Headlight Relay the ground it need to work correctly.
Try you turning on the windshield washer pump I bet either it will not work or the head lights will come on.
Remove the Fuse Block. The Gray connector on the fuse box locate Slot F7 Black wire. Splice a wire into that wire and ground the other end. Now try to start the vehicle.
What do you mean by hot? Hot to touch or hot there is power
Did it arc on you when to grounded the wire and was the key in the on position?
i must have overlooked the second set of grounds (4 total, 2 pairs) behind the block. got it grounded to the head now. used a multimeter to verify that one of them was the same wire as the one i spliced into.
currently, the motor will crank, the headlights work, fuel pump turns on, etc. all electronics seem to work except i still cannot see the pcm with my scan tool...
i am going to put the remaining componets in (spark plugs and wires, air intake, etc.) and see if it will start...
not being able to run diagnostics is kind of bothering me though...
Sorry for the delay I was out of town.
Great you did find a few missed ground wires. I have missed them myself doing intake gaskets before.
Check and make sure fuses ECM B and ECM 1 are not blown, also with the key on make sure you have power at them.
What type of scanner is it?
Check and see if the CIGAR LTR 15 Amp Fuse is Blown. That scanner has to have power from the vehicle to work and it gets it's power from slot 16 on the vehicle Data Link Connector.
If the fuse is good then check and see if you have power a slot 16
If you have power there then you are still missing a ground wire at G105 and G103. just to verify use a volt meter and touch the leads to #16 and #5 then to #16 and #4 on the data link connector. Do you have voltage?
You have a wire pinched some where or the cigarette lighter is bad. Connect your test light to battery positive, remove the fuse and touch the test light to the metal prongs the fuse fits into. which every prong lights the test light up mark it or remember it.
Before we get to deep into looking for this wire, have you replaced and thing inside the vehicle, radio, steering when dash, ect...?
i have an aftermarket radio i put in while the motor was out... shouldnt be an issue but i will disconnect it for troubleshooting purposes...
It won't be the wiring to the radio, there is a chance when you put it in you pinched the wire harness.
Hook the test light to battery positive, remove the fuse and touch the test light to each slot the fuse fits into. The test light should light at one of the slots. Remember which slot light the test light for further testing.
Is there anything in the socket for the cigarette lighter if so remove it and test the fuse slot and see if it lights.
Remove the radio, move the wire harness around, and test the fuse slot. does the test light still light up?
so about 2 years ago i snagged a cigarette lighter out of a FORD at work to put in my truck because i didnt have one... it never worked in my truck and i didnt bother to investigate or take it out of the socket... LOL
when removed from the socket and fused replaced - scantool reads (with no error codes)
it is about to snow here and the truck is outside so i wont be back on it for a couple days. i will try to get it wrapped up and i will let u know how it works out.
i got it figured out now. thanks for your help. you have been extremely valuable. i am accepting to pay you a second time for you help.
New problem: if you would like to try for three???
the motor starts and runs 'decent' but not great. throws code P1345 (Manufacturer Controlled Ignition System or Misfire). ive done some research and it appears to be related to the timing or crank & cam out of correlation.
as part of my rebuild i installed an aftermarket camshaft (COMPCams) and was told i would need to reprogram my PCM to accommodate. They did not mention anything about timing or it throwing trouble codes...
do you think the issue is related to my PCM not compensating for the new cam correctly or would it just be that the mechanical timing is not correct?
this weekend i plan to pull the distributer and re-insert it one spline adv or ret to see if that helps...
Doing a CKP System Variation Learn Procedure may fix the problem, but I am not sure since you have a aftermarket Camshaft installed. The procedure does require a scan tool the can do the CKP System Variation Learn Procedure. Here are the instructions.
Important: For additional diagnostic information, refer to DTC P1336 .
Important: While the learn procedure is in progress, release the throttle immediately when the engine starts to decelerate. The engine control is returned to the operator and the engine responds to throttle position (TP) after the learn procedure is complete.