No crank, no start, possible immobilizer, ECU?

03RAMCOLORADO

MEMBER
2003 DODGE RAM
5.7L
V8
4WD
AUTOMATIC
167,000 MILES

Ignition wouldn't turn with second key (rare use, couldn't find my keys, used many times before) Had aftermarket alarm/remote start. Lights start flashing and horn, etc. I went inside and found my keys fob didn't work. Removed horn fuse. Normal use key would not turn ignition. Disconnected battery, ended up drilling small hole to access release and get ignition cylinder out, started with screwdriver (horn, lights etc, started as soon as neg. Attached to battery). Moved truck into my driveway, removed "pins/plates" from ignition to get a key to turn it, reinstalled and same outcome, except truck died after maybe 3-5 seconds. (Approximately. 3-5 attempts) Few days later tried some things from YouTube, but now no cranking, all lights, stereo, blower fan etc, work. Replaced fuse #14 and got red light to turn off(dash)horn, headlights flashing stopped. Still no crank. Checked dealer w/vin was told no transponder key req. Removed aftermarket start/alarm no change. I can jump the starter relay and crank, can attach wire to yellow wire at ignition to same pin in relay and get crank. Can do same at fuel pump relay, hear it run. But truck will not start/run, nothing when turn the key to start at all. Any help would be great!

3 Replies

KEN L

MASTER CERTIFIED MECHANIC
42,942 POSTS

I'm sorry to hear about the trouble you're experiencing with your 2003 Dodge Ram. It sounds like you've already tried several troubleshooting steps, but let's see if we can help you further.

Based on your description, it appears that the issue might be related to the ignition system or the anti-theft system. Here are a few suggestions you can try:

Check the ignition switch: Ensure that the ignition switch is functioning correctly. It's possible that the switch itself is faulty and needs to be replaced.

Verify the wiring: Double-check all the wiring connections related to the ignition system, alarm, and remote start. Make sure there are no loose or damaged wires. Pay attention to any connections that were modified during the installation of the aftermarket alarm/remote start system.

Reset the anti-theft system: Some Dodge vehicles have an immobilizer system that can cause starting issues. Try disconnecting the battery again and leave it disconnected for about 15 minutes. Then reconnect the battery and see if the issue persists. This reset may help in case the anti-theft system was triggered and is preventing the vehicle from starting.

Check the starter relay: Since you mentioned being able to jump the starter relay and get the engine to crank, it's possible that the relay itself is faulty. Consider replacing the starter relay to see if it resolves the no-crank issue.

Have the vehicle scanned: If the above steps don't resolve the problem, it may be beneficial to have the vehicle scanned for any stored error codes. This can be done using a diagnostic tool or by taking it to a professional mechanic who can perform a thorough inspection and provide more insight into the issue.

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Friday, June 16th, 2023 AT 12:22 PM

03RAMCOLORADO

MEMBER
2 POSTS

I installed a new ignition switch, with no changes, I removed the aftermarket alarm/remote start. I believe that all wires are now connected well. Installed new starter, (was told may be solenoid) no change. Tested relays, multimeter and switching their locations. I was told that there is no anti- on my truck. (By VIN) and only received 2 black keys when purchased 5 or so years ago. (Have looked for an immobilizer bypass and haven't found one. I'm thinking possible bad PCM? Or ECU? I'm unsure on how to test. Also, neutral safety switch? I believe mine is in transmission. (Hope to not do that) Anyone know what color wires are for neutral switch? Thank you in advance! Any suggestions greatly appreciated.

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Friday, June 16th, 2023 AT 3:12 PM

KEN L

MASTER CERTIFIED MECHANIC
42,942 POSTS

I have seen the IPM cause this issue but to be sure we should run a CAN scan. You can get a CAN scanner (Controller Area Network) which will work on most cars from Amazon.

here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

and

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Here is one for about $99.00 if you need it:

https://amzn.to/3ZixY4v

Here is how to change out the IPM in case a code comes up for it. Check out the images (below). Please let us know what happens.

Images (Click to make bigger)