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whats with 98 c5 throws tons of codes after missfire while starting?

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Old 11-07-2018, 01:15 PM
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dlm98conv
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Default whats with 98 c5 throws tons of codes after missfire while starting?

My c5 convertible, auto has 85k miles, is always stored in a garage, never driven in rain or snow. No problems with anything. I went to start it and let off the starter before it fully fired up. For the first time in my history with this car, I hit the key again before the engine had fully stopped turning and the dic lit up with svc traction control and a number of other codes. Resetting didn't remedy and the engine won't fire although it turns over fine. Each time I tried to start it seemed to get worse, even backfired out of the exhaust once while turning over. Any ideas? ECU?
Old 11-07-2018, 01:32 PM
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What are the codes?
Old 11-07-2018, 02:07 PM
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Started out as SVC traction control and antilock brakes warnings on the dic. when I went thru the various codes:TCS C1255, TCS U1016, HVAC BO363, RDCM U1064, SCM U1016, and several more as I didn't record them all. Even got the the "Remove key, wait 10 seconds and retry" After each try I would reset all the codes and once it even started and I backed up, drove forward and every thing seemed fine although I only drove it about 30 feet in each direction, I went over 2 mph to see if the car would work and it did. Next day I was going to take spin and it wouldn't start and codes started pooing up again. Each time I would reset the codes and tried to restart, more codes would come I could hear noises coming from the area of the fuel rails and the single backfire out the exhaust. I believe that most were history codes but still no start. I have a LMC or LC? 5 bypass that has taken car of the column lock problems for 60K miles and didn't think I would ever see the Column look message again.
Very strange!
Old 11-07-2018, 02:25 PM
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disconnect the batt, make sure it has a full charge, rehook it, nothing to lose with trying that ???
Old 11-07-2018, 02:28 PM
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dlm98conv
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I did that several times and charged the battery to 12.8 volts.
Old 11-07-2018, 02:48 PM
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Moved to C5 Tech.
Old 11-07-2018, 03:44 PM
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What DTC's came back after clearing them ??...I went through something similar but I was able to quickly diagnose it as a bad ignition switch....mine was a "no crank no start"...had no 2 second fuel prime either which helped in the diag....now with yours as a "cranking no start" maybe a crank sensor...maybe not...does the tach appear to move while cranking ??...if no you'll get no fuel or spark if crank sensor bad...you can get 10 different opinions here and maybe someone guesses right....I'd do a quick check to see if your PCM is being powered....disconnect your MAF sensor and see if you have the 5 volt reference voltage on the yellow wire with key on engine off... without some diagnostic knowledge and tooling it can be trying !!

Last edited by C5 Diag; 11-07-2018 at 08:37 PM.
Old 11-07-2018, 07:06 PM
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Is the PCM you refer to the same as ECM inside the front fender or are you referring to the silver box in the footwell?
Old 11-07-2018, 07:29 PM
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Originally Posted by dlm98conv
Is the PCM you refer to the same as ECM inside the front fender or are you referring to the silver box in the footwell?
YES !!....PCM/ECM...front fender !!
Old 11-07-2018, 08:44 PM
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Thanks very much!
I don't think this related to ground problems. I removed the 2 plug-in ground connectors on the front frame rails and both are clear of oxidation and have di-electric grease still present in the plugs. I live in Greeley Colorado where humidity is typically very low and don't drive in rain or snow and the car is garaged (heated). Why I say that (not related to poor grounds) is due to what happened to cause the havoc in the system in the first place. i.e. During the starting procedure, it fired but didn't actually start. Before it had a chance to stop turning, I hit the ignition again and that was when the problems showed up.
Old 11-07-2018, 09:03 PM
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If corrosion isn't the problem, would it possibly be ECU failure because I didn't allow time for it to re-set before hitting the starter again? Always in the past, when it didn't fire up, I would wait until the dash reset and never a problem. This problem occurred instantly after I hit the starter? Seems the current was redirected through the system somehow. Maybe it fried the ECU.Thoughts???
Old 11-07-2018, 10:10 PM
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I doubt your PCM is fried...like I had said you can check any of the sensors (TPS,MAF etc) 5 volt references and see if it’s present...you can try to treat this as just a normal cranking no start...a good toot of brake kleen into the engine will check to see if it’s a fuel delivery issue if the car starts or tries to start...also check for that 2 second fuel pump with the key on too !!... what did these noises sound like in the area of your fuel rail ??...l don’t know your mechanical background or knowledge but if it seems that it might be a little over your head to try to diagnose this I’d maybe take it to a good shop !!

Last edited by C5 Diag; 11-07-2018 at 10:28 PM.
Old 11-08-2018, 08:38 PM
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Rob,
Thanks for the info.
I did clean the front frame connectors very thoroughly and scraped off the base of the stud with contact cleaner and a screw driver to get fresh metal and reapplied the dialectric grease. Seems it did wonders, still doesn't start, but the only code now was PO355 C which still came back on the second start attempt as Current after I had cleared the code on the DIC before the second try. PO355 (ignition control #5 Circuit) whatever that is. I also Checked the voltage at the MAF sensor yellow wire and it was 5.4 volts.
That's a relief. I don't think I heard the fuel pump and I didn't try spraying carb cleaner into the intake yet. I'm thinking maybe that #5 circuit is the fuel pump. What are your thoughts?
You have been extremely helpful and I thank you very much!!!!
Dennis
Old 11-08-2018, 10:22 PM
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Hey Dennis !!...the 0355 is an issue with the ignition control circuit on #5 cylinder...even if only cylinder 5 was dead the car should still start if fuel system is good...the PCM WILL disable the #5 fuel injector too BTW with that DTC!!...first thing to do is see if you have spark...disconnect the plug wire from the coil and connect 12 volt test light to ground...have someone crank the engine over and see if the spark jumps from the coil to the tip of the test light....I would check # 5 and another cylinder (try the other bank- passenger side)...if no spark at #5 only you can check the ignition circuit now or later if you do have spark at the other cylinders... coil has 4 wires...first I would make sure that the connector is secure to the coil...now disconnect the connector..,pink is 12v...green is control (from PCM)...black is ground and I think it’s brown but that’s your low reference (ground)...you can check it if you want with a multimeter and a 12 volt test light...with key on engine off you should have 12 volts on the pink...green (control) is around 1 volt or less but only while the engine is running...might be same if just cranking but I think PCM just needs to see an RPM signal ...now with your test light connected to battery positive (you can use the alternators red cable instead of using the battery... the test light will light when you connect it to the last 2 wires...black and brown. If spark good try the brake kleen and see if the car trys to start.

Last edited by C5 Diag; 11-09-2018 at 12:02 PM.
Old 11-08-2018, 11:10 PM
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Dennis,
if spark is good at all cylinders....maybe not at #5....like I said try the brake kleen...if car starts or try’s to start you have a fuel delivery problem (fuel pump or injector control)...if no 2 second prime when the key is turned on check fuse #13 (F/PMP) and see if it's blown...if not swap the horn relay with the fuel pump relay in the under hood fuse box...now listen and see if you hear the pump come on for 2 seconds...if still no start we can check the fuel pump relay circuit with the relay removed but if fuel pump does come on we can check for injector control !!...p.s. I was thinking ignition relay 42 might be bad but the PCM was alive but we can look at that possibly !!

Last edited by C5 Diag; 11-09-2018 at 08:22 AM.
Old 11-09-2018, 11:58 AM
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^^ could be simple fuel problem that hit you at the wrong time. Get a gauge on there, turn the key to "on" see what happens. Some auto parts stores will rent them
Old 11-09-2018, 12:05 PM
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Just to get things clear in my head,,, Can you turn the ignition switch to ON/RUN, Press RESET and clear any messages that appear in the DIC. Enter the DTC reading tool and CLEAR ALL DTCs. Then attempt to crank and start the engine. If it fails, WITHOUT turning off the ignition (leave it in ON/RUN),, Press reset again if there are any messages in the DIC and then read and post ALL the DTCs that you see.

Thanks...

Bill

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To whats with 98 c5 throws tons of codes after missfire while starting?

Old 11-12-2018, 06:53 PM
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Hopefully, we can narrow this down.-Tach doesn't move when it turns with starter.-MAF has 5.4 volts -no spark (I checked #3 & 4 spark plugs/coil with a light probe and no spark) didn't bother checking the rest, although I did spray carb cleaner into the intake with no result. -I do hear the fuel pump for a couple seconds, although it seems to repeat itself a few times if I leave the key on, kinda like it is maintaining pressure. Sometimes fuel pump runs for 15-20 seconds and does it after a minute or so it stops for a while then repeats. Today, while I was trying to start it after resetting the DIC it popped? or backfired again out of the exhaust. Should I pull an injector or two to see if they are squirting? I assume I'm hearing the fuel pump as the sound comes from the area of the fuel rails towards the back--Fuse #13 F/PMP is good.-Swapped the horn relay with the fuel pump relay. Didn't do anything that I could detect.-still getting lots of codes after trying to start a couple times. ? Each time I would try, I reset the DIC codes that would show up, but not get the same results. sometimes it would be SVC TRACTION SYS, SVS ACTIVE HANDLG, 10-PCM PO335 C, TCS U1016 H, IPC U1016H, HVAC BO363 H.Other times it would not include the ACTIVE HANDLING & SVC TRACTION SYS but would include left & right door modules or seats or IPC. most are typically Loss of communication,Doesn't seem like there is any consistency.Thanks for your thoughts!!Dennis
Old 11-12-2018, 07:57 PM
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Hey Dennis !!...no Tach movement during cranking is a good indication of no crank sensor signal PLUS I see you have a P0335...that is a crank sensor DTC...well that’s why your not getting spark !!...as far as the fuel pump with the key ON your pump will come on for 2 seconds and shut off. You really don’t have to physically remove the injector...all we want to do is check for 12 volts and “injector pulse” at the injector. I’m 99% sure you don’t have it but let’s check anyways!!...Just disconnect an injector and take your test light connected to battery NEGATIVE and see if your test light lights touching the PINK wire ...if good now connect the test light to battery POSITIVE and see if the test light lights and flickers while you try to start at the other wire...I believe they are all striped wires...if you’re not getting ignition the PCM isn’t going to fire the fuel injectors...now before you had a P0355 right (ignition control circuit) ???...thinking maybe you transposed some numbers. Well I would hate to say that YES it’s a definitely bad crank sensor without testing the circuit but if you want to try it (at the PCM) and if not you’d have to yank the starter to get to the crank sensor...I have some long piercing probes and I don’t think they’d work...let us know what direction you might want to go !!

Last edited by C5 Diag; 11-12-2018 at 08:00 PM.
Old 11-12-2018, 08:59 PM
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I did transpose the 335 & 355, I will check the voltage tomorrow and get back to you. I don’t mind taking the starter out if that’s what it takes.
Thanks for your help!
I learn something new every day!


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