1993 Z28 won't start. Can jump starter still won't run - CamaroZ28.Com Message Board


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Old 05-12-2017, 11:19 PM   #1
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Question 1993 Z28 won't start. Can jump starter still won't run

Hey y'all hopefully you can help me. I've got a 93 Z28 M6 and a few months ago it decided it didn't want to start anymore. Here's a list of what I've checked.

Starter- good
Ignition switch- replaced
Battery voltage- good
Jump wire for starter- only cranks when jumped directly to power.
Fuses on drivers side & relay box under hood
Fuel pump- good
Bypass clutch switch
Discharged the battery


When you turn the key on lights on come on in the cluster but when you go to crank it it will not engage the starter. All you hear is a relay click once. I pin pointed said relay and it's on the drivers side at the firewall near the console. I've seen folks talk about VATS but my security light is not on. It seems to me that it's not getting spark when I jump the starter cause it cranks fine and that makes me believe there is something in the cranking process that isn't allowing spark. Like I said it won't crank from the key but it will crank with the purple wire jumped. Yes, it has good compression as well. The car ran like a dream a few months ago so some component has failed. Hope y'all can help I hate seeing her like this. Thanks
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Old 05-13-2017, 07:41 AM   #2
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Re: 1993 Z28 won't start. Can jump starter still won't run

There is a switch under the dash that when you push the clutch in makes a connection so the car will start.I also have a standard shift saturn vue and my switch looks a little deformed from all the pressure it gets from constant usage and I'm sure it's going to have to be replaced soon.Also,did you try your spare key?Hope this helps.
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Old 05-13-2017, 07:49 AM   #3
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Re: 1993 Z28 won't start. Can jump starter still won't run

If you are not getting power to the purple wire at the starter when the key is turned to START, then you need to use a meter to trace back through the circuit to see where it stops. It goes from ignition switch>starter enable relay>clutch switch>starter.

http://shbox.com/1/starter_charging_93.jpg
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Old 05-13-2017, 03:08 PM   #4
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Re: 1993 Z28 won't start. Can jump starter still won't run

fatdog2, are you referring to the clutch switch? If so I unplugged it and I've got it bypassed with a paper clip in it. That's the only switch I could see on the pedal. As for another key, I've only had one set of keys for this car since I got it in 98.

Shoebox, I doubt I'm getting power to the purple wire on start. I ran a separate wire to the starter to jump it off since I had the starter off. I'll check the diagram, I just assumed if I could setup a push button start that it would run but it seems something isn't allowing spark with the key on and jumping the starter.
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Old 05-13-2017, 08:06 PM   #5
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Re: 1993 Z28 won't start. Can jump starter still won't run

Typically there are two switches on the clutch, one to close the starter circuit when the clutch is depressed, and another to release the cruise control. Are you sure you have the right switch?

Is the "SECURITY" light on steady? .... or flashing? The PASS-Key system disables the fuel pump when the key is not read correctly. Is it possible that it is absence of fuel that is preventing it from starting, and not absence of spark?

Do the dash warning lights turn on when you turn the key to run/start? Did you check the fusible link that supplies the "start" circuit? See the diagram Shoebox linked.
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Old 05-13-2017, 08:19 PM   #6
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Re: 1993 Z28 won't start. Can jump starter still won't run

No the security light is not on....
I'm getting fuel, I can hear the pump and my gauge is reading almost 40psi.
I'll climb under there later and see if I can see another switch.
Yes, all the reg lights come on when you turn the ignition on. When you turn it to start all you hear is one relay click at the floorboard against the firewall.
I don't get a chance to work on the car every day so I'll check over the diagram as soon as I can.
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Old 05-13-2017, 11:01 PM   #7
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Re: 1993 Z28 won't start. Can jump starter still won't run

I picked up my Camaro a couple of years ago with one key for the ignition and bought another key and went to the dealer and had it programmed.It has a chip in it and I've heard the chip can ware down especially if it is combined with my other keys grinding away over the years.My saturn key last summer started to give me problems where I would put the key in and turn it to the on position and the dash lights came on but car would not start.No clicking just dead.Pulled the key out,put it back in,and it would start.It did this for about two weeks,so I grabbed my other (new) key I had laying around and haven't looked back since.Starts right up every time.Hope this helps.
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Old 05-14-2017, 09:35 AM   #8
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Re: 1993 Z28 won't start. Can jump starter still won't run

When do you hear the fuel pump running? It will only run for two seconds when you turn the key to "run", then shuts down, holding the pressure at ~40 PSI with the check valve in the fuel pump. Fuel pump does not restart until 1) the PCM receives the signal from the TDM (theft detterant module) indicating the key has been read correctly; AND 2) the PCM sees the low resolution pulse signal from cam position sensor in the Optispark distributor. If the pump restarts while cranking the engine, those two required conditions are being met, and are not the issue.

The "chip" in the key is nothing more than a simple resistor. It can't be "programmed". About the only thing that can go wrong with it is dirty or worn contacts.
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Old 05-14-2017, 11:50 AM   #9
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Re: 1993 Z28 won't start. Can jump starter still won't run

You can hear the pump when the key is turned on. You can also smell fuel after you've tried to crank it. I don't think it's a VATS issue since the security light is not on and key is fine.
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Old 05-14-2017, 12:11 PM   #10
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Re: 1993 Z28 won't start. Can jump starter still won't run

When the key is in the "run" position the pump only runs for two seconds. Can you hear it restart when you turn the key to "start"? Reference the circuit diagram - there is no "on" position for the key.
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Old 05-14-2017, 09:49 PM   #11
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Re: 1993 Z28 won't start. Can jump starter still won't run

I may have missed it, but I don't see where you said the Security light ever comes on. It should be on for several seconds at ignition-on time.
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Old 05-18-2017, 08:02 PM   #12
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Re: 1993 Z28 won't start. Can jump starter still won't run

Alright Gents, here's an update. I have another 93 Z28 in the family A4. With the key on his security light comes on for the bulb test. Mine does not. Most likely it is VATS not allowing ignition. Also tonight messing with it the key will come out of the ignition in the on/start position so that can't be helping either...
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Old 05-18-2017, 09:31 PM   #13
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Re: 1993 Z28 won't start. Can jump starter still won't run

If it's the vats relay, where is it? I found the starter relay and the one next to it. Swapped them since they are the same and no changes.
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Old 05-19-2017, 12:21 AM   #14
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Re: 1993 Z28 won't start. Can jump starter still won't run

My saturn did that.I could pull the key out while the engine was running.GM had a recall and they replaced the whole assembly in the steering column and gave me new keys to boot for free.I would go to a GM dealer with your VIN number and get a new key.My02.
Side note: The new keys also worked on the doors.Hope this helps.
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Old 05-19-2017, 10:56 AM   #15
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Re: 1993 Z28 won't start. Can jump starter still won't run

Quote:
Originally Posted by 93Z28t56 View Post
If it's the vats relay, where is it? I found the starter relay and the one next to it. Swapped them since they are the same and no changes.
Info on PASS-Key II system, including component locations.

Courtesy of Shoebox

4th Gen LT1 F-Body Tech-PassKey/VATS

Quote:
The TDR can sometimes be at fault. It is located to the right of the glove box, next to the hatch relay. It is pinned to the metal structure of the dashboard. It is easiest to see if you poke your head under the dashboard and look back toward the rear (after removing the lower dash panel).
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