RXPX

Cliff Notes:

(1) P1518 and 'Reduced Engine Power' during hard bump or WOT pull

(2) Pressing on Ignition Relay causes relay to go bad

(3) Ignition switch requires calmly cycling through the positions in order for car to start properly.

(4) Ignition Relay keeps going bad.



Hello all, I'm new here but have visited this site before joining plenty of times. There's so much helpful information on this site, its awesome!

I usually try to read and search things before I resort to asking a question or making a thread. I'm a little stumped and unfortunately I've been having some electrical gremlins causing problems with the car.

I've definitely read, read and read some more. I've come to a point of which I have a rough idea of what the problem is and what the usual fix is.

Here is what I've worked out after a lot of troubleshooting.

If I turn the ignition switch to the 'Start' position too fast, the car will only crank and not start. If I calmly cycle through all 3 positions and wait for the fuel prime to go through, the car will start correctly. Sometimes it'll set DTC P1518 and 'Reduced Engine Power'. If I enter the diagnostic mode while the code is 'current' I can clear it and the car will run/idle correctly.

Here's where it gets rough, I'd really appreciate some help

If I do a WOT pull or hit a bump while driving, specifically while applying the brakes, the car sets off the Reduced Engine Power, ABS and Active Handling warning lights. It also randomly sets off random codes that it's never used to set.

These are the latest codes:

P1518 is the common code. And the only code out of these that will be 'C' current.

These I've only had pop up once. I noticed most of these where possibly 'low voltage' codes, which makes me suspect the ignition switch even further.

P0443
P0449
P0645
P0803

Clearing the codes removes them so thankfully they're not current or 'C' only P1518 is current.

So from everything I've read I've learned that some of the recommendations are cleaning the grounds, diagnosing ignition switch and sometimes even battery replacement.

Ive actually replaced 3 of the 4 engine bay grounds. The battery seems to be working great, the starter crank always sounds strong.

Here's one question I have, under Bill's 'C5 Ignition Switch Repair' He says the listed fuses should have power in both the ACC and ON position. Mine only have power in the ON position and twice while testing, it actually took a few seconds for me to see voltage. So the fact that I only have power in the ON position, does that point to the ignition switch as the culprit?

Here's where it gets more interesting. Before going through the grounds, the car somehow 'damaged' the ignition relay. It was setting DTC P1518 and would only crank but not start. So I pop a new relay in and the car starts perfectly fine without the code. After replacing the relay, with the car running, I press down on the relay and the car shuts off burning out the relay. I replace the relay once again and went ahead and repaired some of the engine bay grounds. Some did have corrosive build up, so I went ahead and crimped new lugs. I also sanded down the grounding areas and insulated with electrical tape. I haven't tried purposely 'shorting' out the relay again. But a relay should not burn out by pressing on it with the engine running, correct?

What would cause the relay to go bad just by simply pressing on it while it's running? I once read that, in some cases, relays can go bad if they're receiving low voltage, compared to what they're supposed to receive. Not sure how true that is? I do know that a faulty switch sends out improper voltage. Most if not all of the DTCs show the possibility of being set due to low voltage.

Sorry for the long post. I'm just trying to be as detailed as I can, and I am a bit tired, haha. I'm just worried that these two things are not related and that they might be separate problems.

Thanks for taking the time to read.

Bill Curlee

THE VERY FIRST THING THAT YOU NEED TO DO IS REPLACE OR CLEAN THE IGNITION SWITCH!!!

That may solve a LOT of your issues right off the bat!!

- C5 ignition Switch repair - http://forums.corvetteforum.com/c5-t...ch-repair.html

RXPX

Bill! I feel like I'm one step closer to solving my problem just knowing you've replied! Thank you for everything that you have contributed to this forum sir.

I'm definitely going to be doing the switch repair. The thread you've created is already bookmarked on my browser. I'm in Texas and according to the news, there might be a tropical storm hitting sometime today.

I used the diagnostic steps in your 'C5 Ignition Repair' thread. I have the proper 12.5ish volts on every fuse but ONLY with the ignition in the 'ON' position. On the first two times, I noticed it took a good 2-3 seconds before I got voltage at those points. I had no voltage with the key in the 'ACC' only in the 'ON' position. It's still possible that it could be the switch, correct? I'm going remove and repair it anyway to play it safe.

I actually have an update Bill, last night the car would not start no matter what I did. It quickly set the 'Reduced Engine Power/P1518' with a crank no start. Today while the weather was somewhat calm, I suspected the relay was at fault again. So I threw in a replacement and the car fired right up. I was up very late last night digging through a lot of old threads related to the 'P1518' code. I read a lot of good info with plenty of pointers and tips. You're definitely in plenty of them. Here's the thing, out of like the 40 or so threads that I read through, none of them kept burning out the ignition relay.

What could cause a relay to keep going bad? These aren't cheap relays either, I've been using Tyco and Semens brand relays.

I read low voltage can create resistance, which in turn creates heat, which then burns the coil inside the relay. But I don't know too much about electrical circuits and components.

RXPX

Hey Bill, I will definitely be repairing the ignition switch as soon as the weather clears up. But if I press on the ignition relay while it's running, the car shuts off and the relay goes bad. I have to replace the relay in order for the car to start again. Any ideas? I saw once that the fuse block internally is a lot of copper traces and was basically not serviceable.

dadaroo

I have worked on several cases where the internal fuse box terminals are bad or the internal connection is bad. This would create a low voltage condition that could "fry" the relay. Have you taken a relay apart to see? Pressing on the relay causing the car to die sure indicates a possible fuse box issue.

Internal fuse box problems can/may be fixed if that is it. Or, you can get another one from Marc at VetteNuts.com. They all appear to be the same but the internals can to wired differently from what I have been told. Marc could match you up with the correct one just in case.

I also agree to make sure the ignition electrical switch is removed from the equation for a number of the other issues.

Mr. Sam

RXPX

Yes, I'm definitely going to repair the contacts on the ignition switch. If anything it'll at least be for preventative maintenance.

But they'res definitely something wrong with the terminals for the ignition relay on the fuse block. It's already damaged 4 separate relays. I have not taken one apart yet though.

So as soon as the rain stops falling, (currently there's a 'tropical storm' that landed here in Texas yesterday.) I'll be removing the ignition switch for repair and possibly running some diagnostic procedures found on my manual for the ignition relay. I hope it'll help me find a short/open or possibly loose/bad contacts on the block.

Thanks for the input, Mr. Sam. I'm feeling a little better now, like we're starting to get closer to the problem.

Marc@Vettenuts.net

We can get you a used replacement ignition switch with key or a fuse box. We have a C5 in now that is driving us crazy with no communication issues that come and go. We have replaced everything but the fuse box and its coming out today!

Marc

RXPX

Hey Marc,

Thanks for your reply.

Would it be possible for you to take pictures of the R/R of the fuse box? I took a look at how I'd go about removing it the day I went through the chassis grounds in case it did end up being the culprit. I saw a few bolts that had to be undone but noticed all the wiring running to it and didn't know where it would unplug from.

As far as the fuse box coming out, will you be repairing the old box or dropping in a new one?

PM me a price on a fuse box, just in case.

RXPX

It gets frustrating, ahh! haha

I go out there, open the door and it starts raining so I come back in. Rain stops. haha

So I have the console out, and dash bezel/trim slightly off. I was just about to get to the ignition switch when it starts raining.

While removing the shift ****, I assumed it was like any other **** and used the old 'reverse thread' method. Now that I've looked it up and saw that there is actually a key under the shift pattern logo. I kind of twisted pretty hard beforehand, now I'm a little concerned it was too hard.

I will keep the thread updated for anyone who is interested. I'm trying to take pictures as I go. It's hard with the Texas rain, humidity and heat.

Bill Curlee

MARC

Call me to discuss this NO COMMS issue.

PM Sent

RXPX

Bill, Mr.Sam and Marc, thanks to all of you for giving me your input. It really is appreciated.

I have an update, too early to tell but I'm excited. So far it seems as if the problem has been resolved!

I removed and disassembled the ignition switch. Sure enough, both the pin and switch contacts had black marks on basically all but one contact.

Bill I feel dumb, but I could not figure out how to OHM out the contacts per your thread. I'm not the best when it comes to this stuff. The best I could come up with was setting the DMM at the 'OHMs' position at 2000. Then I'd probe the corresponding contacts. My readings didn't seem to change much regardless of where I was probing so I assumed I did it wrong.

I sanded the contacts and entire pins with 2000 grit, then cleaned them up with alcohol. They came out great with a polished look!

I re-installed the ignition switch and installed a new ignition relay. It turned on with the first try! The car would intermittently burn the relay either with time, or by slightly pressing on the top of the relay with the car running. So with the car running, I pressed on the relay and even gently moved it just a tiny bit. Tried it a few times and car stayed running!

It's too early to call it, only driving it and maybe time will tell, but it looks as once again the ignition switch repair has been succesful! haha

Bill Curlee

I would guess by now you have old relays laying around. Get the MALE pin out of one of the relays. Insert that PIN into the FEMALE pin slots in the fuse box. You should feel insertion and extration resistance when moving the male pin in and out of the female pin.

IF,,, the male pin is LOOSE in the female pin, theres a possible cause of the heat damage and high current draw on that relay.

Bill

Bill

RXPX

Yes I have plenty of bad relays laying around. I'll be sure to do that as soon as I get a chance. I know removing/installing the relay has resistance.

I also noticed the car turns on much faster now, almost instantly. And I moved the relay pretty hard while the car was running and it didn't blow the relay or shut the car off this time.

Only other thing I've noticed is the relay feels warm while the others are cold.

I'll post back when I try an individual pin.

Thanks again Bill! I'd be more than happy to PayPal you enough for a 6 pack!

Marc@Vettenuts.net

Im glad you figured it out. I changed the fuse box in my 99 and still no comms and reduced engine power. I have changed the BCM, KEY and cleaned all grounds. The problem was coming and going now its all the time.

Bill any ideas?

Bill Curlee

I sent you a PM with my Cell# Please call me lets discuss... I do have ideas..

BC

RXPX

Hey Marc thanks!

I'm sure you'll quickly figure out what the issue is, especially with Bill's help.

I'm sure you've most likely already checked, but is the Ignition relay good? You can swap it out with the cooling fan relay just to test it out.

Mine used to also be intermittent for a good period of time. Suddenly it would no longer start until I'd replace the relay.

dadaroo

Actually on a manual you don't need to remove the shift **** to remove the console. Just loosen the boot from the console and rotate it so that you can lift the console up. The boo and shift know remain in place.

RXPX

That's actually how I had it at first when I couldn't figure out how to get it removed. Eventually I came in to figure out the removal procedure. I wanted to remove it completeley since they'res a couple of things I plan on doing to the head unit and hvac display.

RXPX

I called it too soon guys, it gave me the same crank no start with code C1518.

I tried clearing the code but it would remain as H and C. After a few minutes, it finally cleared and the car started as normal.

I'm stumped. Could it be possible that my switch has already burned up the contacts? I recently rebuilt the ignition switch about a week ago. After the rebuild all the symptoms were gone.

dadaroo

Maybe. I have not seen the switch contacts and they could have a light coating of material to reduce arcing pitting that may get removed by sanding. I guess you may need to pull it and take a look.