Riddle me this no start issue
Thread Starter
Instructor
Joined: Apr 2022
Posts: 142
Likes: 48
From: Central NY State
Riddle me this no start issue
So my 93 has been running great for months. Drove it the other day and when I got home, had some oil burning off my passenger side cat, looked like my dipstick was loose and blowing a little oil out of it. So this weekend I pulled my PCV valve to check it. Rattles and looked good. Just put it back in, got in and started it, and things acted very weird. High idle (1500 rpm), security light on left of tach comes on, then a sys flashing on digital speedo, then check engine light and ASR light. I shut it off. Go under hood checking things. Get back in and now I it won't do anything, turn key, nothing. Help! For now I disconnected the neg batt cable with a kill switch I have on it.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
Sounds pretty straight forward to me; you have a poor electrical connection somewhere, OR the battery took a complete dump. The first possibility is far more likely than the second. Hook your battery back up, get a meter or test light and start looking for your bad connection. 
Thread Starter
Instructor
Joined: Apr 2022
Posts: 142
Likes: 48
From: Central NY State
Sounds pretty straight forward to me; you have a poor electrical connection somewhere, OR the battery took a complete dump. The first possibility is far more likely than the second. Hook your battery back up, get a meter or test light and start looking for your bad connection.
When I turn my key to on, the fans kick on, even with the AC off. When I go from key on to start the emergency brake light comes on. I just had my ECM reflowed earlier this year. I tried two of my other keys thinking it was the VATS acting up. I'll start looking for a shorted wire I guess, that will be a nightmare.
Drifting
Joined: Jun 2020
Posts: 1,355
Likes: 396
From: Northwest Ohio
ECM would not cause the engine to not crank. I.e. you are stating the engine is not cranking at all (no starter engagement)? You turn the key to start and nothing happens?
I would try bypassing your kill switch and check all of the connections by the battery. Probe for voltage. Check for shorted alternator…all kinds of things.
I would try bypassing your kill switch and check all of the connections by the battery. Probe for voltage. Check for shorted alternator…all kinds of things.
Thread Starter
Instructor
Joined: Apr 2022
Posts: 142
Likes: 48
From: Central NY State
ECM would not cause the engine to not crank. I.e. you are stating the engine is not cranking at all (no starter engagement)? You turn the key to start and nothing happens?
I would try bypassing your kill switch and check all of the connections by the battery. Probe for voltage. Check for shorted alternator…all kinds of things.
I would try bypassing your kill switch and check all of the connections by the battery. Probe for voltage. Check for shorted alternator…all kinds of things.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
Don't stop there! The battery connections aren't the only connections. You checked the battery connections....that's good. You say you have power there, so where's the power go next? The starter. So go to the starter, see if you have a good connection and power at the starter. Then, where's the power go from there? To the power distribution center/fuse box....so go there. Do that until you get to a place were you're not getting power (and thus, the starter motor doesn't run), and you should then be well on your way to understanding the problem. And don't forget; grounds are part of "bad connections".
Drifting
Joined: Jun 2020
Posts: 1,355
Likes: 396
From: Northwest Ohio
I agree about the ECM, but a dead/flaked out ECM shouldn’t prevent crank, it will allow a crank (controlled by CCM) but no fuel enable (I know this first hand)….
His symptoms while running were in alignment with ECM issues (comm bus problems triggering ASR light, SYS message, sec light blinking while running etc)…but that’s not a no crank situation.
Seems like a bad ground…and I’d pull the kill switch out of the loop too. Trace the power flow and make sure grounds are clean!
His symptoms while running were in alignment with ECM issues (comm bus problems triggering ASR light, SYS message, sec light blinking while running etc)…but that’s not a no crank situation.
Seems like a bad ground…and I’d pull the kill switch out of the loop too. Trace the power flow and make sure grounds are clean!
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Thread Starter
Instructor
Joined: Apr 2022
Posts: 142
Likes: 48
From: Central NY State
I agree about the ECM, but a dead/flaked out ECM shouldn’t prevent crank, it will allow a crank (controlled by CCM) but no fuel enable (I know this first hand)….
His symptoms while running were in alignment with ECM issues (comm bus problems triggering ASR light, SYS message, sec light blinking while running etc)…but that’s not a no crank situation.
Seems like a bad ground…and I’d pull the kill switch out of the loop too. Trace the power flow and make sure grounds are clean!
His symptoms while running were in alignment with ECM issues (comm bus problems triggering ASR light, SYS message, sec light blinking while running etc)…but that’s not a no crank situation.
Seems like a bad ground…and I’d pull the kill switch out of the loop too. Trace the power flow and make sure grounds are clean!
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
Could be. Test it.
There are Grounds on the bottom left corner of the block., some to the frame on the driver's side, for starters. But man....I'd sure want to know if I got power to the starter motor, second (since you checked the batt terms...
There are Grounds on the bottom left corner of the block., some to the frame on the driver's side, for starters. But man....I'd sure want to know if I got power to the starter motor, second (since you checked the batt terms...
Thread Starter
Instructor
Joined: Apr 2022
Posts: 142
Likes: 48
From: Central NY State
Thread Starter
Instructor
Joined: Apr 2022
Posts: 142
Likes: 48
From: Central NY State
One thing I recalled this morning is when it did start up and was idling high.......if I gave it any gas it just bogged down instead of ramping up in rpm.
Gotta dig into tracing electrical, but man this is frustrating. It took me two months to get it running great again, enjoyed it reliably for two months and now out of no where this.
Gotta dig into tracing electrical, but man this is frustrating. It took me two months to get it running great again, enjoyed it reliably for two months and now out of no where this.
Instructor
Joined: Sep 2022
Posts: 209
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From: Dalbo, Minnesota
A few thoughts -
original problem. Check for loose vacuum lines or a cracked hose. Go ahead and replace the pcv valve. They do wear out even if they rattle.
electric gremlins - do your car a favor and don’t use a boost charger. These chargers can spike the system with 60 volts. They rely on the battery to clip the spikes to safe levels, which it will do as long as the battery and all connections are good. If the battery is flat, disconnected, or there are poor connections it can damage the older electronics never designed for this type of charging. Some charges will not attempt to charge a flat or damaged battery for this reason.
edit- forgot to add. Fans come on with ignition? paper clip in ALDL port?
original problem. Check for loose vacuum lines or a cracked hose. Go ahead and replace the pcv valve. They do wear out even if they rattle.
electric gremlins - do your car a favor and don’t use a boost charger. These chargers can spike the system with 60 volts. They rely on the battery to clip the spikes to safe levels, which it will do as long as the battery and all connections are good. If the battery is flat, disconnected, or there are poor connections it can damage the older electronics never designed for this type of charging. Some charges will not attempt to charge a flat or damaged battery for this reason.
edit- forgot to add. Fans come on with ignition? paper clip in ALDL port?
Last edited by Talfryyn; Nov 1, 2022 at 01:50 PM. Reason: CRS
Thread Starter
Instructor
Joined: Apr 2022
Posts: 142
Likes: 48
From: Central NY State
A few thoughts -
original problem. Check for loose vacuum lines or a cracked hose. Go ahead and replace the pcv valve. They do wear out even if they rattle.
electric gremlins - do your car a favor and don’t use a boost charger. These chargers can spike the system with 60 volts. They rely on the battery to clip the spikes to safe levels, which it will do as long as the battery and all connections are good. If the battery is flat, disconnected, or there are poor connections it can damage the older electronics never designed for this type of charging. Some charges will not attempt to charge a flat or damaged battery for this reason.
edit- forgot to add. Fans come on with ignition? paper clip in ALDL port?
original problem. Check for loose vacuum lines or a cracked hose. Go ahead and replace the pcv valve. They do wear out even if they rattle.
electric gremlins - do your car a favor and don’t use a boost charger. These chargers can spike the system with 60 volts. They rely on the battery to clip the spikes to safe levels, which it will do as long as the battery and all connections are good. If the battery is flat, disconnected, or there are poor connections it can damage the older electronics never designed for this type of charging. Some charges will not attempt to charge a flat or damaged battery for this reason.
edit- forgot to add. Fans come on with ignition? paper clip in ALDL port?
I never thought of the booster being bad for things, hopefully it just blew a CCM fuse or something like that. I have to pull my fuses and see what's what.
I also have to jumper the A and G pins to see about codes. Yes the fans come on with AC off with key on. Not a great sign to me. SIA reflowed my ECM a few months ago.
So I have a lot of diagnostic things to run through, maybe one day this week after work or this coming weekend.
Thread Starter
Instructor
Joined: Apr 2022
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From: Central NY State
Update
So far with a little time I’ve checked a few things.
battery connections good, voltage 12.4
lead to alternator reads same 12.4
jumpered to pull codes…none
started checking fuses for ccm, ignition etc. all visually look good, need to do a continuity test on them too.
next steps are jacking it up and getting under the car to check voltage at starter and all the block grounds.
Fans are still coming on with key on everything else off on climate control.
I just can’t believe after messing with Pcv and possibly have a bad leak or Pcv which caused the engine to run like ****, and try and restart and I get nothing. Like the limp mode the computer went into fried something in the ecm
So far with a little time I’ve checked a few things.
battery connections good, voltage 12.4
lead to alternator reads same 12.4
jumpered to pull codes…none
started checking fuses for ccm, ignition etc. all visually look good, need to do a continuity test on them too.
next steps are jacking it up and getting under the car to check voltage at starter and all the block grounds.
Fans are still coming on with key on everything else off on climate control.
I just can’t believe after messing with Pcv and possibly have a bad leak or Pcv which caused the engine to run like ****, and try and restart and I get nothing. Like the limp mode the computer went into fried something in the ecm
Drifting
Joined: Jun 2020
Posts: 1,355
Likes: 396
From: Northwest Ohio
I believe it will still crank even without the ECM plugged in…so figure that out first. I don’t believe it has anything to do with the crank circuit (CCM does, starter does, relays do, good connections do). Is your LCD lighting up when you turn the key to on?
Perhaps you have something shorted somewhere. Check voltage, fuses, fuseable links…
Perhaps you have something shorted somewhere. Check voltage, fuses, fuseable links…
Thread Starter
Instructor
Joined: Apr 2022
Posts: 142
Likes: 48
From: Central NY State
I believe it will still crank even without the ECM plugged in…so figure that out first. I don’t believe it has anything to do with the crank circuit (CCM does, starter does, relays do, good connections do). Is your LCD lighting up when you turn the key to on?
Perhaps you have something shorted somewhere. Check voltage, fuses, fuseable links…
Perhaps you have something shorted somewhere. Check voltage, fuses, fuseable links…
Yes my LCD lights up as normal with key on.
Drifting
Joined: Jun 2020
Posts: 1,355
Likes: 396
From: Northwest Ohio
Looked it up to 100% confirm… FSM, book 2, 8A-30-0 is the diagram. Nothing from the ECM at play….
Ignition switch, to clutch/crank fuse to clutch switch to starter relay. Starter relay is enabled/ grounded by the CCM via VATS enablement. Then from starter relay to starter solenoid.
To confirm security light is not ON when you try to crank?
My hot take: whatever ground the CCM is using is bad OR main block ground is bad…ground term/cable on batt bad…. Check Voltage between positive terminal and the block and chassis.
You will likely see no 12V at the solenoid of the starter.
Ignition switch, to clutch/crank fuse to clutch switch to starter relay. Starter relay is enabled/ grounded by the CCM via VATS enablement. Then from starter relay to starter solenoid.
To confirm security light is not ON when you try to crank?
My hot take: whatever ground the CCM is using is bad OR main block ground is bad…ground term/cable on batt bad…. Check Voltage between positive terminal and the block and chassis.
You will likely see no 12V at the solenoid of the starter.
Thread Starter
Instructor
Joined: Apr 2022
Posts: 142
Likes: 48
From: Central NY State
Looked it up to 100% confirm… FSM, book 2, 8A-30-0 is the diagram. Nothing from the ECM at play….
Ignition switch, to clutch/crank fuse to clutch switch to starter relay. Starter relay is enabled/ grounded by the CCM via VATS enablement. Then from starter relay to starter solenoid.
To confirm security light is not ON when you try to crank?
My hot take: whatever ground the CCM is using is bad OR main block ground is bad…ground term/cable on batt bad…. Check Voltage between positive terminal and the block and chassis.
You will likely see no 12V at the solenoid of the starter.
Ignition switch, to clutch/crank fuse to clutch switch to starter relay. Starter relay is enabled/ grounded by the CCM via VATS enablement. Then from starter relay to starter solenoid.
To confirm security light is not ON when you try to crank?
My hot take: whatever ground the CCM is using is bad OR main block ground is bad…ground term/cable on batt bad…. Check Voltage between positive terminal and the block and chassis.
You will likely see no 12V at the solenoid of the starter.
Will check the security light, along with the other things you listed. Fingers crossed I find the culprit.
On a side note, I'm having trouble finding that little 180 PCV hose on drivers side intake manifold. Mines dry rotted and cracked. 3/8" GM6165M part number. NAPA didn't have anything close, and normal vac hose kinks. Might have to create my own with a union and two piece to minimize the bend.