Will leaving Ignition key on kill ECU box?

[MoparGuy68]

Please tell me if what I did today could have damaged my ECU box.

I have an Ehrenberg Hi-Rev 7500 ECU that I bought a couple months ago. In preparation for jacking up the rear end of my car and putting it under jackstands I moved the automatic transmission gear selector into neutral. I did this because I was planning on rotating the rear wheels and counting the number of turns the driveshaft made to figure out my current gear ratio.

I did not disconnect the battery before doing this, which I probably should have done. I turned the ignition key one click forward to allow the transmission to be shifted into neutral. Is the ignition on at that point, and is power going to the ECU you when you do this?

I got occupied examining the wheels when I took them off the car. The ignition key was in this position for probably a good two hours. Then I put the wheels back on, lowered the car on the ground put the transmission in park, and cranked the engine. The engine would not start.. I cranked so many times I lost count. This is the first time since I’ve owned the car I’ve not been able to start the engine. It was getting dark so I have not done the test for spark by pulling off a coil wire or a plug wire yet. Prior to doing all this the car had been sitting for one week, so I know it has nothing to do with carburetor heat soak, or vapor lock. As the engine was cold.

I’m writing this post to check if I have just learned another lesson, the hard way, by ruining my new ECU.

I still have the old made in China ECU that was on the car when I bought it. But I have another problem, with the Hi-Rev ECU that I never fixed after I installed it. When I installed the Hi-Rev and plugged in the wire connector, I then attempted to screw in the securing Phillips head screw that’s meant to keep the wire connector from coming off the ECU unit. That damn screw did NOT screw into the Hi-Rev box properly. And would not TIGHTEN and seat snug like it is supposed to. It just spins around as if the female threaded hole in the box is stripped. This exact screw worked fine with the made in China box and a Mopar Performance orange box. I only had problems with it on the Hi-Rev box.

So now the screw is stuck on the Hi-Rev box and I cannot get it out, therefore I cannot disconnect the wire harness from the Hi-Rev ECU box. The screw just spins in place in both directions clockwise and counterclockwise, not moving forward and not moving backward. The only thing I can think of doing is taking a hacksaw and trying to saw the head off of the screw so I can free the wire harness from the box.

 

[MoparGuy68]

I am thinking about this more.. When the key is moved to that first click forward position that allows the column shifter to be moved out of Park to Neutral the ignition should be OFF at that position. I had to look this up in my Operators Manual to confirm.

There are five positions that the key can be in from forward most to rear most position as listed below:

1 Start
2 ON
3 OFF
4 Lock
5 Accessory

I left my key in position 3 for two hours. Turning the key from the Lock to OFF position before jacking up the car. So the ECU should not have been receiving any power during that two hour time..

i’ll have to do some more troubleshooting, but it looks like I couldn’t have damaged my ECU if the ignition was in the OFF position..

 

[451Mopar]

It could be the ballast resistor, coil, dist pickup, or the ECU?
Disconnect the coil - connection to the ECU,
Power on the ignition. You should see very near full battery voltage at both the + and - coil terminals.
If no voltage, replace the ballast resistor.
Pull the coil wire from cap and use a jumper wire connected the the coil - and tap to ground, and it should create a spark at the coil.
If no spark, replace the ignition coil (or coil wire?)
Remove the jumper wire from coil -, and tap the - Coil wire from the ECU to the coil - like the jumper wire. A normal ECU should ground the coil when the engine is not spinning, so there should be a spark from the ignition coil. I don't know if the ECU you have works the same as a stock unit?
There are a few other tests you can do checking the ECU harness and ground connections, but swapping a known good ECU is quicker when you think the ECU may be bad.

 

[66 Sat]

If the screw turns both ways freely but doesn't bite, try pulling on it gently with the some long nose pliers while turning it counter clockwise to try to get onto the thread. Once it bites it should come out if you continue to turn it counter clockwise without pressing down, just enough to keep the screwdriver in contact with the head. If you can get something behind the end of the screw you can apply pressure that way too while turning but I'm not sure you can.

 

[Nacho-RT74]

There is no power to anywhere in Off position.

And about the Hi-Rev7500 ECU. I have my doubts about their quality. I have used mine for 2 weeks while my Rev-N-Nator arrived and worked good, but that's it, just used for 2 weeks. A Friend of mine used for his Dart 74 and just worked for 3 or 4 months untill died just like any cheap ECU.

Yes, about the fastener for the screw mounted on ECU it seems to be weak and easy to spread up the thread, just like any newer China product. I bet you will be able to pull out the ECU plug just applying some force and the fastener on ECU will come out attached to the screw ( BTDT on some ECU around ).

Try to catch the screw head with plyers and get it screwed out while pulling out at the same time to check if works

Anyway I have run my Car without that screw for years, and plug never jumped out or came out loose.

I'm about request to my friend who got his unit damaged to open the box and check for the inners, included the power transistor.

 

[65-440]

I've been running a Jegs hi-rev 7500 box for 6yrs now with no issues. I put it in after 2 orange box failures!
About your initial question, no it will not kill the ECU. Should be no different then when the car is running, voltage is always applied to the ECU. Whats your battery voltage at?

 

[HALIFAXHOPS]

I have to add my 2 cents here. I have been testing them lately pretty hard. That RE box is a good one. All the ecu's I have tested draw around 4 amps not running ( *key on) and around 2.5 running. Just what I found out. Plan on doing a comprehensive thread on this one day with vids and pics. You decide. Hope it helps.

 

[69Bee]

If you left your door open for the two'ish hours, your interior light was on. Charge the battery, and try again.

 

[Daves69]

If the screw turns both ways freely but doesn't bite, try pulling on it gently with the some long nose pliers while turning it counter clockwise to try to get onto the thread........

.......

 

[slepr1]

Email Richard E. and let him know about that stripped screw. He's always been good to me for answering quickly. If all else fails and you need to get that screw out, just drill the head off of it.

 

[451Mopar]

If the ECU is like a stock one then leaving the key on, engine not running puts more load (constant current) through the ECU power transistor, so it could cause damage if the transistor gets too hot. The current it sinks will depend on the Ballast resistor and coil primary resistance.
When the engine is running the power transistor is switching on and off, and the coils impedance will reduce the amount of average current flowing through the power transistor.

 

[Don Frelier]

I think the vice grip idea will work.
Otherwise try some plastic wedges and slide a narrow one beneath the molded plug and push the plug off while backing off the screw.
That should take care of it.

 

[MoparGuy68]

If you left your door open for the two'ish hours, your interior light was on. Charge the battery, and try again.

This is the strangest reply, so I have to respond to it. Nowhere did I say that I left my door open for two hours. I left the ignition key in the OFF position for two hours. When I started this thread, I mistakenly thought that I had left the key in the ON position.

I removed my interior dome light bulb and turned off the instrument cluster light switch over a year ago, in preparation for spending the rest of my life working on this very old and neglected car. The battery was fully charged prior to cranking the engine. Nothing wrong with either the battery or the starter motor. It most definitely is either a fuel or electrical ignition problem. Of the two I suspect ignition..

 

[MoparGuy68]

Thanks for the suggestions for removing the securing screw. When I manage to get the screw out I will contact Ehrenberg and tell him about it. As there is nothing he can do about it now.

Looks like I’ll be troubleshooting all next weekend..

 

[Rydog73charger]

I got occupied examining the wheels when I took them off the car. The ignition key was in this position for probably a good two hours. Then I put the wheels back on, lowered the car on the ground put the transmission in park, and cranked the engine. The engine would not start.. I cranked so many times I lost count.

Hey while reading this I found an important detail, you put the trans back in park to start it. Did you happen to try to crank the vehicle in neutral?

 

[65-440]

Hey while reading this I found an important detail, you put the trans back in park to start it. Did you happen to try to crank the vehicle in neutral?

What's the difference? He's not having a cranking issues

 

[Rydog73charger]

What's the difference? He's not having a cranking issues

It's to make sure the car doesn't think its in the wrong gear while starting.
I've had a similar problem before on my car. I rolled the car out of the garage to work on it, tried to start it in park, wouldn't start. Put the car back in neutral and it started right up.

 

[65-440]

It's to make sure the car doesn't think its in the wrong gear while starting.
I've had a similar problem before on my car. I rolled the car out of the garage to work on it, tried to start it in park, wouldn't start. Put the car back in neutral and it started right up.

As in anything but park / neutral? If his engine is turning over but not firing that should eliminate a neutral safety switch issue...
Was your engine not turning over in park but it did in neutral?

 

[Ron H]

I had similar stripped screw on mine, I have a prong tool I use for removing door panels that comes in handy for a lot of other things, if you have one slip it behind the screw head creating outward pressure while turning the screw CC. A small needle nose pliers should work as well or slip in a flat blade screwdriver. As for crank and no start you're ECU requires a good ground...sure you're aware; but tossing it out: Check for spark at a plug wire and see if that's the demon, check your connections, coil, etc. also with all the cranking if you can't detect any gas odor that's a signal..

 

[69Bee]

This is the strangest reply, so I have to respond to it. Nowhere did I say that I left my door open for two hours. I left the ignition key in the OFF position for two hours. When I started this thread, I mistakenly thought that I had left the key in the ON position.

I removed my interior dome light bulb and turned off the instrument cluster light switch over a year ago, in preparation for spending the rest of my life working on this very old and neglected car. The battery was fully charged prior to cranking the engine. Nothing wrong with either the battery or the starter motor. It most definitely is either a fuel or electrical ignition problem. Of the two I suspect ignition..

You are correct, you didn't say you left the door open, BUT you also did NOT say that you didn't either. We are all just spitballing here, so I'm sorry for my assistance.