What prompted the battery upgrade of my other post:

A couple weeks ago, out of the blue, within a block of my home, but not at startup, the ABS and Traction Control trouble lights illuminated and the warnings appeared on the Driver Information Center. The car also started missing. I turned it around and parked it in the garage, and noticed that the remote did not work.

After sporadic hours of searching this forum, and Google, over the next couple weeks,, then using the DIC, I determined that code C1255 could indicate several underlying issues, especially when coupled with the miss and key fobs not working.

So, I checked the battery voltage, which read 11.9. I pulled it out and had it tested; it had a bad cell, so I set off to replace it and install the Big 3 upgrade. However, I ordered the incorrect Big 3 (my bad) top mount. So, I purchased an Optima, because it was the only battery in stock with both side and top terminals, which are now all in use.

I also checked the large fuses under the hood, disassembled and cleaned the three grounding points under the hood, and drove the car about 30 miles to charge the battery. The miss went anyway and the remotes worked after synchronization. But, still the ABS and Traction Control warnings were there.

I hooked up a Snap-On scan tool because I was hoping to find a wheel sensor with no reading (another enumerated cause of the dreaded C1255) but found something curious, with the engine running, it read 13.7 volts at the battery but 0.0 "switch voltage" at the EBTCM.

I turned the engine off, pulled the wiring harness from the EBTCM, and read the pin voltage with the key on. There were 3 wires on the pump side of the wiring which read 12.44 volts. There was only one wire on the EBTCM side which read 5.0 volts, but the wire was Orange with a Black stripe. According the a diagram I found online, for a 1999 EBTCM, the only wire which should read any voltage is a Gray wire with 5.0 "reference" volts.

What should I check next? I've looked for any information regarding a relay or a connection that would be called into question, but to no avail. There are no wires or connections that look compromised. The car is a 37,000 mile garage queen, so it hasn't had a hard life.

Thank you.

 

LOL!! As I was reading your post it hit me what could be your issue. If you are reading less than battery voltage on the EBTCM Ignition Switched powered leg, the IGNITION SWITCH is at fault. They are a well documented cause of numerous electrical issues. The contacts inside the switch get burnt and pass less than actual battery voltage. The modules do NOT like that! I hope the 1255 is a result of the low voltage supplied to the module and not because the low voltage killed the module.

I have a post that explains how to service the switch but it is a LOT easier to just purchase a new switch. Get a new switch and we can go over how to get the OEM key cylinder out of the old and into the new switch. Its easy.

Bill

 

Bill, thank you for the heads up. My research revealed that the ignition switch could be the problem, BUT since there was proper voltage across the two fuses, I, mistakenly, crossed that off the list. I will purchase an ignition switch forthwith.

Again, thank you. Bob

 

I pulled the old switch out, and it appears to have issues.



Bill, I read your post about how to rebuild the switch, but I decided to order a new AC Delco switch. I followed your instructions and removed the key cylinder. Thank you.

Hopefully, on Wednesday I will post another update.

 

You may not be out of the woods as of yet. I strongly recommend that you carefully examine the ignition switch harness female connectors. Look at them both for bent/spread apart female pins pins. Very common issue and it has caused more than one C5 owner heart aches! Its best to conduct a proper pin PUSH / PULL test with a male pin inside the female pins to see if there is proper grip on the male pin when it is inserted and retracted.

BC

 

Can somebody explain what the issues with the switch shown in the photos are?

It looks like other than a small amount of oxidation on the contacts, the unit appears to be in normal condition... or am I not seeing that the looks a little cooked (hard to tell having never seen one before)

 

The oxidation may prevent full current from passing through, thus triggering the ABS and TractionControl warning lights.

 

The saga continues. So, I ordered a Delco replacement switch for parts store. Installed it, and not only would the car not start, but it made the battery appear to be bad by knocking it down to 25% charge. So, I had to pull the new battery out and have it load tested. In the meantime, if took apart the original ignition switch and cleaned it. So, when you received the battery back, I installed the original switch and the car started, but still had the warnings and Snap-On scan tool showed 0.0 switch voltage. So I exchanged the Delco switch for the store brand and tried again.

With the off brand switch, the car started, still had the warnings and showed 0.0 switch voltage. But, this switch was very jerky. It was not smooth at all as it cycled through it's different positions. So, I returned it also, and am back to the original switch. And problem.

 

Bill, I do appreciate and value your input. But since I show full voltage at the megafuse under the hood, and 5 volts for reference at the EBCM pin, how could a poor switch connection cause this problem?

I am wondering if the problem is on the EBCM board, which I can not check due to this type of set up.

Again, thank you for all of your guidance.

Bob

 

So now, along with SERVICE TRACTION SYSTEM and SERVICE ABS, I get the SERVICE COLUMN LOCK warning. But, I installed LCM5 Module last year after the steering column locked last year!

 

The mega fuses power the ignition switch. The switch has 3-4 internal contacts that supply voltage to different "IGNITION SWITCH POWERED MODULES" If the output of the ignition switch is compromised and not able to provide the proper VOLTAGE "and " proper CURRENT to the modules, that module/s will not function properly.

The best way to determine if your switch is working correctly is to do a voltage & current test at the "IGNITION SWITCH" powered fuse/s for the modules/circuits in question...
Use a big incandescent lamp on the ignition switch fused module circuit and make sure that the lamp lights bright and the voltage stays at full battery voltage under load. If the circuit cant supply the proper voltage AND load, it wont work correctly. Each fuse has two test points on top of the fuse. Make test and measurements there on both pins to ground.

You need to carefully examine the TWO FEMALE ignition switch female connectors. The female pins in those connectors are WELL KNOWN to spread apart and make a POOR connection, Well you know the rest,,, of the story when that happens... Do a proper male pin PUSH PULL test on the female pins and see if you have good female pins with the proper GRIP on the male pins! I've Seen TWO recent Forum members with a similar issue and the female pins were trashed.

There could be other issues but, we have to start at the beginning of the circuit and that's where Ive seen numerous electrical issues. Rule that out and lets continue.

Bill