My car didn't come with it's code and I've left a message with my service department but wondering if anyone knows how to retrieve the anti-theft number as my original dealer didn't include it for us. I've had the car battery disconnected for a couple days as I was working on it and now it won't start - key fobs lock/unlock the car but I'm getting the red immobiliser light and the radio is asking for the anti-theft number.

 

Dealer called back - the radio anti-theft is unrelated to my won't start issue. Anti-theft code can be bypassed which I did. Won't start is something else - fob is recognised and it cranks but won't start and I get the flashing red immobiliser light in my dash as that's happening. Looks like I will need to get it towed in.

 

Does the same thing happen with the 2nd key.?

 

Yep, fob will lock and unlock the car and will allow cranking but I get the red immobiliser light flashing in accessory mode. Talked to dealer again and I'm gonna get it towed in - thinks it might be that the immobiliser has forgotten our keys (or is faulty which is not likely). The immobiliser is separate from the ignition or anti-theft system.

 

I notice that you are in Canada. Does your FOB have the ability to remote start? How about the AcuraLink App?

If the receiver for the key fob signal is not working, then perhaps either of these will work for you?

I also suggest checking the fuses in the 3 under hood boxes and the 3 interior boxes. There can't be much else that would cause the problem.

EDIT: You could also try holding the FOB close to the start button, as you would do with a dead fob battery.

 

Remote start doesn't work - same result as in car, it cranks once and then errors out. Haven't tried AcuraLink yet - I don't have access to my account anymore. Also tried holding it up close to the start button with the same result. I checked the inside fuse boxes and they're fine - I thought maybe I had dislodged something as I had the whole interior out of the car but it checks out. Will check the outside fuse box in the morning. Thanks for all the suggestions - would love to avoid a tow to the dealer!

 

For those interested in what happened - because the battery had been disconnected for 2 days the immobilizer had gone into "PDI" mode per the service advisor (the state the car is in when it's just been delivered to the dealer) and it required a really hard push on the brake pedal to trigger the system. Along with that the brake pressure had been lost over the 2 days so the press had to be a very hard push. Fixed in an hour by the dealer at no charge.

Lesson: Don't leave your RDX's battery disconnected for long but if you do expect to have to press the brake pedal very, very hard to get it going again.

 

I appreciate you posting to let us know the final solution.

I do recall that when I disconnected my battery, for a reason I can't remember now, it took several attempts at cranking before the engine started. My first thoughts were of panic since I thought an electrical surge had fried a component.

When it finally started I assumed the the ECM had just needed a few minutes to relearn the fuel trims etc. and I never thought any more about it until today.

Perhaps after my first couple of attempts, the panic caused me to press on the brake pedal extra firmly.

​​​​​​It sounds like this reset method uses the same switch as the automatic brake hold. I don't know if this is a 2nd switch on the brake pedal, or if it is a pressure switch connected to the brake line, but I do know it is not the same switch that turns on the brake lights. I can hold the RDX stationary (while in drive) using the brake, but it takes extra pressure to activate the automatic brake hold.

 

A wild guess of mine is that b/c the brake booster is electric rather than hydraulic that disconnecting the battery for a long time is what leads to the problem I encountered - the system can't pressurize again till the engine is running but the engine won't run because there wasn't enough brake pressure applied to the pedal (and boosted by the booster) to get the engine to start.

 

Is this anything like " It takes money to make money" ? LOL

 

I was detailing my RDX in the driveway, & probably left the ignition on over night. My fault. I charged the battery, & tried to start. The starter turned over fine, but no start, & the Red Immobilizer/Security light flashed in the cluster. Called Acura Roadside assistance & got towed to the dealer. Not impressed with the fact that the flatbed driver had to drag the car onto the flatbed, because you can't put the transmission in neutral, without the car running. Driver had plastic skis for the tires, to reduce abuse to the driveline & transmission park pin.

Dealer fixed no start issue in less than 30 seconds, with a secret start sequence, that's not in the user manual.

Feet off the pedals, push the start button twice to get into run mode, with the cluster gauges on. Vigorously press the brake pedal, & then release, repeat brake pedal & release one more time. Feet off the pedals, press the start button once to turn the gauges off. Put your foot on the brake pedal & push the start button to start the car, as you normally would.

Dealer didn't charge me a penny, & covered the tow.

 

You just saved me! This worked perfectly.

 

You saved me too! 🙌🏼

 

If you search through the (pdf version of the) owner manual for 'immobilizer', you will find that there are different instructions for Canada for this crank but no start after battery unhooked situation. The instructions (for Canada)

Canadian models only: Apply and hold the brake
pedal before turning the vehicle on the first time after
the battery has been disconnected.

There is another section that says to push brake firmly then start button, then release brake fully then start (stop) button. I have no idea why the US and Canada instruction would be any different.

 

Hi, I wanted to ask how did you bypass the code? I cannot find my Anti Theft Code either and I had turned the battery off for like 2 minutes. And the code needed screen won’t go away from my radio.

 

Just push and hold the audio power button for more than 2 seconds.

That causes the radio to compare it's internal ID with the one stored in the RDX's computer. If they match, then the radio belongs in that vehicle, and it becomes unlocked. If the numbers don't match, then that radio came from somewhere else, and it will remain locked.

 

this saves me as well. After replacing car battery today, I had same issue (red immobalizer light flashing). The procedure works great and I have engine started. Thank you very much

 

Subscribing for the future - in case I need this!

 

Well, let me be the first to thank you for this . I have been trying everything to get my car running after disconnecting the battery: Exact same symptoms as you, with the slow-flash immobilizer LED. AI suggestions had me going down a rabbit hole of trying various ways to re-pair the key fob and the vehicle, and nothing worked. I was kicking myself for losing my manual with the 5-digit radio code, but it turns out that was another rabbit hole: Just press and hold the power button and the radio is fine.

The hard-press of the brake pedal did it. I went to the garage, fully doubting that such a simple thing would work and... it worked. I did see it in the manual, but it wasn't clear that it had to be a really hard press.

Thank you!
John