Hi everyone, I recently bought a project 2001 C5 manual and I am currently facing a no start issue. Before going into detail and what I have done to troubleshoot I feel I should provide a little background if it helps... I bought the car a few weeks ago from an owner who was going to turbo the vette but during the disassembling of the engine he claims he also tried installing a killswitch and somehow or someway a cable mounted underneath the glove box shorted and many wires burnt badly to the point the blower also started melting! On top of that previous owner claimed out of panic that he cut the PCM wires underneath the hood fuse box (why not disconnect the battery?) to kill the car. Long story short thanks to many of the longtime members' threads which provided diagrams and how to's for wiring, troubleshooting and disassembling the dash, I was able to remove almost everything and install a new harness inside the car for the same year options and manual. Thanks to diagrams I was able to reconnect the wiring for the PCM to the underhood fuse box, after a few days all the electronics worked there is communication with the PCM BCM IPC and all other modules.....

While tackling the engine wiring we came to find that we had some missing connectors and mechanically headers, spark plugs, even things like the intake manifold were not tighten correctly. ( I am assuming since he did not include the turbo set up he was installing he just placed everything back together quickly) Now we tried starting the car and noticed the starter is doing its job and the battery is above 12.3v but I could not hear the fuel pump and did not see any spark with testing, we came to find that some of those connectors were for the Camshaft sensor as well as the Oil sensor, we took the manifold and installed them and the fuel pump was now working! but unfortunately again there was no spark still.... so now I question if its the Crankshaft sensor??? I do not have any codes for the PCM the BCM or the IPC, I have checked the grounds on the doors since I installed the harness, I did check the grounds underneath the battery and the one underneath the headers near the starter. Now the reason I suspect the CPS is because I never connected that cable because its not with the engine wiring harness that came with the car, I do have some connectors left which I will provide pictures (which I suspect are for the cats or stock headers) but none of them are a 3 pin Dark Blue, Yellow, Green like wiring diagram suggests. The wiring diagram does show that clearly these 3 wires go to the PCM so I am confident that I am missing, the connector or perhaps previous owner cut these wires cause they're hard to reach??? I am hoping someone would elaborate and confirm that the CPS wires indeed are part of the engine wiring harness and where the split point is so I can see if he cut them or where to look as I cannot find pictures of the wiring route itself only through the wiring diagram. Or if the wires are not part of the wiring harness where they lead to then? Any help is appreciated and thank you

 

All I can suggest is find the 3 CKP sensor wires at the PCM if both connectors are installed and see where their at !!...do you have the wiring schematic for both of the PCM connectors ??..,I’ll look at my ‘01 FSM and see if it shows the CKP routing !!

 

Does your tachometer move when cranking, could be the crank sensor wiring or crank sensor itself.

 

yes i do have schematic! I will do that today after work, I am confident I will have the wires start from the PCM I am guessing they will be cut somewhere

 

the tach does animate but when cranking I don't see the tach move. It just cranks healthy. I am leaning towards the wiring since I don't recall ever installing that since it's not in the engine wiring that came with the car, do you happen to know if the cable for the crank sensor is part of the engine wiring harness? I will be removing the headers and starter to check if there is anything plugged in

 

I was able to reach near the starter and indeed realized there’s nothing plugged in to the CKP connector, bought a pigtail and installed the wires correctly, reassembled everything again but now I’m getting not only NO start because there’s no spark, but I don’t hear the fuel pump anymore. Can anyone elaborate where to look now? I’m thinking of taking everything out again checking the grounds underneath the battery, next to the block and the starter. Would it be a possibility that the crankshaft sensor is bad? I have no PCM IPC or BCM codes either

 

There's I think 2 ground wires that get bolted to the back of one of the heads,try and check that.

 

To diagnose the CKP see if you have spark while cranking...next take a 12 volt test light connected to battery POSITIVE...remove an easy injector connector...while cranking probe the wire that is not the pink wire...it’s a striped wire...as you are cranking the test light will blink as the engine is being cranked...if no spark and injector pulse you have a bad CKP OR wiring !!...the 3 CKP wires are power, ground, and a signal !!..below is the pin out for my 01 CKP.

 

Near the MAP sensor and the Brake Booster Vacuum line? If so I did connect those a week ago when connecting the Camshaft and MAP sensor, when I got to that point I did hear the pump working but I still had no spark. It was until the day after when I connected the CKP sensor that was broken from the wire with a new pigtail that the pump stopped priming and no spark still. I’m checking now as we speak to troubleshoot again

 

thank you for this! I will definitely test that out, I am hoping that either my wiring is incorrect or the sensor is bad. I’ll keep you guys updated today.

 

I would recheck your wiring AND the CKP wiring from the PCM !!

 

I just did the test with the test light, and got no spark or light blinking, tried it on another injector cable with the striped wire like you mentioned and same result. Checking the wiring for the CKP sensor now

 

OK, if no spark from a coil pack or no injector pulse you’re looking at a bad CKP or wiring or both !!

 

Okay! I’m on my way removing the headers, I did some analysis on the wiring where I joined the 3 cables. I unwired them to replicate at the situation I was before (where I did not have anything connected to the CKP and the fuel pump was priming) but I was not able to replicate that scenario. I did see that the blue wire was giving around 4.1 4.3 ohms with the power off...... Anyways I’m still going to check that I have the connections at the connector correct.... and if they are correct I’ll try and start the vehicle. If that fails I’m going to purchase the sensor and try again. In case that fails could there be any other reason? I’m certain that the CKP sensor is the culprit. Will keep updated

 

Resistance isn’t a real valid test for the signal wire (and also for grounds)...I did a test with my own car a few years back to see what you would see cranking the engine over with a DVOM...I back probed the signal wire at the PCM and during cranking all I saw was about 4-5 volts !!...since this is a pull up circuit you would normally see 12 volts cranking but only with a scope...a DVOM only averages the voltage and if the duty cycle of the signal is 50% for instance that 12 volts will only be 6 volts and with the duty cycle of 50% you can divide that by 2 so you’re only looking at 3 volts roughly !!

 

sorry for the late reply, I was able to yesterday remove the starter and replace the CKP sensor and check the wires. So new sensor, wires looked great. Checked ground on side of the engine block, checked wires on the starter, checked wires on the under hood prefuse box, charged the battery..... and no start or fuel pump priming ......... what could I be missing? Is there anything else to lookout for? I am removing today the intake manifold to check the Camshaft sensor. It does have a new sensor since a week ago I changed it and that’s what initially made progress and got the pump to function.... now that week ago when I inserted the key and the pump tan for the first time there was a leak on the driver side injector 8. So I immediately turn the ignition off and realized it was missing the o ring. Replaced it and it wouldn’t close fully with the clip from the fuel rail. After that the pump stopped working again. Then after a couple of minutes it worked again and the day after that when I installed the new pigtail for the CKP sensor the fuel pump stopped priming again. Am I missing something here with the fuel rail? The PO removed the oring and I had trouble fitting it with new oring. Would that be a no start no spark issue?? I also have some cables left where I can’t seem to find the connectors, I know some are the O2 for the headers but this car has LTs installed I’m attaching a video showing the cables I have left. Again thank you!

 

Wires “looking great” doesn’t tell me a lot !!...like I said you have to check power, low reference (ground) and the signal wire as in the video...did you use an OEM sensor ??...aftermarket (Dorman) are JUNK !!
even with a bad cam sensor the car WILL still start...however a little longer !!

 

Here is the YouTube link to me explaining what I have left and what it’s experiencing, the description also gives an overview in case it’s hard to hear or understand. Thank you

 

Sorry for the late reply! I have been in the process of moving to another apartment and that has kept me from doing further testing... I will be doing that test in the following days to properly diagnose. I did install an aftermarket CKP sensor, I do still have the original though. Now i do have an update..... So I towed the car to the new place and installed the fully charged battery and tried to see if by luck it would start or tell me something new, luckily it did tell me something new. So I read in the manuals when troubleshooting the Cam and CKP sensor to test if they are faulty is to crank the car for 15 seconds. Which i did, and thankfully i received CODES! so with this new information I received the following...

10PCM - P0335 C , P1637 H C , P1638 H C

28TCS - C1232 H C , C1233 H C , C1248 H C , C1295 H C ( I believe the 1232 1233 are my unconnected wheel speed sensors...)

A6 SCM - B2606 ( reclining seat position is not working )

B0 RFA - U1000 H C

Also the radiator fan would turn on when the car is on the key OFF position and would turn off with key position in ON (weird) and the headlights pop up and light up when also switching key ON ( the light switch lever is on OFF though)


Now I think the most interesting are obviously the PCM codes and the U1000 RFA code. After doing some research so far I found the U1000 is a loss of communication with a XXX module correct? It should be accompanied by another Uxxxx code stating the module where signal was lost or interrupted, but it does not. I have read that the U1000 code appears alone when reconnecting a battery, I am open to interpretations.

Now as far as the P0335 goes the CKP Sensor Circuit is likely the culprit and as you told me C5 Diag that it could be the crappy new sensor OR checking the power, low reference ground and signal wire link that you sent me. I did read however when paired with P1637 and P1638 code it could be either that it needs a relearning procedure or perhaps the PCM is bad or different????? I do not know what the PO has done other than the mods he listed to me, but I am worried now that the PCM this car has installed may be possibly different? I hope I am not going paranoid, or looking too hard into this, any other inputs arre very appreciated and again thank you C5 Diag for the help you have provided.

 

fuses 16 and 22 feed both the coils and the injectors. Is relay 42 energizing? The CKP does not control power circuits to the inj’s and coils, but will keep the engine from running. So far with no test lighting at the inj, suggests no power or ground. Since no spark, seems it would be something common to both (relay 42?) Like wise the fuel pump does not wait on the ckp either.

I suggest you back up and trouble shoot volts and grounds to the inj’s and coils. There are actually 2 grounds on the coil primary side, so you need to chase +12v . Then, if you get relay 42 to energize, you should be getting spark and fuel to start. Yes the ckp needs to be fixed, but that may be a problem created attempting to solve another problem.

The mindset you need to keep when electrical troubleshooting is, in the end (99.9% of the time), there is only one problem, fix it and all is good.