Stubborn Crank, No Start
#21
03-22-2019, 11:54 AM
The adventure begins. Are you ready to do some tracing/measuring/eliminating to find your problem? I'll be glad to help you but we will go through a logical process. There are other members better suited to the part swapping approach or "one time this was the problem ..." That approach can get to the bottom of it eventually but its time and money.
George
George
Last edited by GeorgeLG; 03-22-2019 at 12:44 PM.
#22
03-22-2019, 12:58 PM
Yeah thatd be great. I printed off the diagrams for this circuit under the hood and have a power Probe that got me this far. Any help would be greatly appreciated
#23
03-22-2019, 01:39 PM
A number of systems get powered when the ignition switch is in either the run and/or start positions. There is more than one wire/color heading to a variety of fuses/systems. The pink wire that leaves the ignition switch on its way to the ECM1 fuse passes through a connector (C5) on the way that branches off also as a pink wire and feeds the Gauges fuse 4, SIR fuse 16, and turn fuse 10. Please check the power into those 3 fuses with key on/run. Those 3 fuses are in the I/P fuse block. Always check power using the battery ground to rule out a bad ground.
George
George
#24
03-22-2019, 06:48 PM
Lets go alllll the way back to the beginning here. When the shop jump started it, it took right off. Have you gone back and tested the battery? I ask because I had a similar issue this past winter and my battery is weak. Short term solution to get me through the cold weather before replacing the battery was to have one of my 'spare' top post batteries and a set of jumper cables on hand in the truck. Jumping the battery increased the available cranking amps and it would light up immediately. The battery itself can charge up to 13.1 volts but it's old and just doesn't have the stamina it used to. Jump it and if it starts right up, it could be a simple as your battery needs replaced since it's dropping too low under load to provide enough juice.
#25
03-22-2019, 07:09 PM
I had swapped battery previously it is a good battery. No voltage at those 3 fuses. I found the C5 connector it has 12v coming out of the underhood fuse block. I assume its the same two larger gauge red wires feeding the IP block they have 12v there as well
#26
03-22-2019, 09:06 PM
At the c5 connector there will be three pink wires (at least). One sending 12v from the ignition switch to the connector at then 12v being sent to the ecm1fuse and again on the other pink wire to the three fuses you just tested. Given that the three fuses are dead that means that there is either a problem with the connector, a problem somewhere in the pink wire from the ignition switch, power to the ignition switch or the ignition switch itself. On one of my diagrams that connector is labeled as c5 and c211, don’t know what that means. C211 also has the main red wire bringing power to the ignition switch. We need to get to the pink wire that is the output from the ignition switch into the connector and measure voltage. We also need to confirm power out of the ignition A fuse which heads to the ignition switch on a red wire and confirm good power to the ignition switch. You are almost there. The quality of the battery does not matter at this point because the nodes that we are measuring are completely dead with a battery putting out 12v. When we clear this up then the quality of the battery may affect cranking or ignition.
George
George
#29
03-23-2019, 08:08 AM
Ive got it that was the problem. No voltage until I pulled the entire connector down and wiggled it around. Put some zip ties around it and cranked them down. Now have 12v to those circuits but Blazer still wont start even after a snort of starting fluid. Now comes sorting through what the previous mechanic did. He reportedly had his hands on the coil, ICM, and cam sensor in the distributor.
#30
03-23-2019, 09:26 AM
Because of the wonky c211 connector make sure you check voltage at the ecm1fuse every time we start any other ingnition tests so that we are not chasing our tail. That said:
the output from the Ecm1 fuse is a series of more pink power wires to power the CPS, fuel injectors, ICM, coil, pcm and vcm. With key on check for power on the pink wires for BOTH the coil and the ICM.
is there still no spark at the plugs during cranking?
George
the output from the Ecm1 fuse is a series of more pink power wires to power the CPS, fuel injectors, ICM, coil, pcm and vcm. With key on check for power on the pink wires for BOTH the coil and the ICM.
is there still no spark at the plugs during cranking?
George