I moved my car about 2 weeks ago and put it in the middle of the driveway to do some work to change out a leaking intercooler; fast-forward to today, I'm finished and tried to start the car. No crank and I thought that was funny, so I grabbed the jump cable and nothing; I decided I'd put a charger on and come back later and check it out, but still no dice.

I jumped the wire in the fuse box to see if the starter would trigger, and it did, but there was no fuel pressure, so it's like the anti-thief isn't powering the EFI circuit since there isn't power to my standalone to turn on the fuel pumps.

Does the alarm system cut power to EFI and the starter? Where can I find it under the TSRM Im trying to find anything about it but it doesn't seem like it's in there.

 

Hello,

First of all, which car is it that you have issues with?

The the sole responsibility of the Theft Deterrent ECU in this case is to cut the Ground Wire to the Starter Relay, it doesn't have anything to do with the Power on either EFI Relay or Fuse, here is a thread about it in case anyone else needs it in the future.

Check where the Power is Missing, use a Test Light to check ALL the Fuses in the car. Without knowing your exact setup, it's pretty hard to tell what's missing, considering that you have a Standalone ECU and very likely bypassed Fuel Pump ECU, considering that you referred to Pumps in plural.. Find the EFI and Ignition Wires in your New Harness and make sure that they are Powered when needed, if not, you will have to find a Diagram you used when splicing the Wiring and find which Fuse was supposed to power the respective Wire. If you have a Factory Service Manual for this car with Wiring Diagrams, look up Power Source page, which tells how exactly each Fuse is Powered.

Hope this helps and best of luck!

 

I have a 98 SC300 with a stock computer in parallel with an ECU master black. It's very strange. I'm thinking that somehow my ignition switch failed or something, but it doesn't explain why I'm not getting power on +BATT wire on the ECU which is supposed to be live all the time?

 

The Pin BATT, at least according to the GS diagram, don't have anything on a Facelift SC, is powered directly from the 25A EFI Fuse, which in turn, if the Power Source Diagram is to be trusted, is powered straight from the Battery. If you don't have Power on the BATT Terminal, the first logical step would be to check the EFI Fuse, and preferably ALL the other Fuses as well, just in case. If the Fuse is intact, 12V comes To it, and then Leaves the Fuse, follow the Diagram that you likely have for your car to see if anything else that is Powered from the EFI Fuse has said Power coming to it, which will show if there is an issue with the Wiring.

Hope this helps and best of luck!

 

Jesus, I feel stupid.

I unplugged the bottom connector under the fuse box, needing the space to get to the fender liner plastic square screw-in holder. This explains why there was no power as it left the fuse box but never made it to the ECU as it was disconnected right after the fuse box. That being solved now, when I turn the ignition to ON i hear my fuel pump trigger from my standalone meaning there is power going to both ECU's. Also I confirmed this by connected to the stock ECU via OBD2 port.

The next challenge is when I plug in this connector, the dash cluster turns off! The gauges go black, and the time and mileage displays go off. Yet when I unplug it again they both turn on. WTF? Also trying to start the car the starter will not trigger when it's plugged in.

A quick check in the TSRM and it claims the power for the cluster comes from CIG fuse, which is good, and also checked the kick pannel. Regardless of that, unplugging that connector under the fuse box and making it go on proves the fuses are good. So WTH would cause these to go off?

Going to keep searching it's late and I'm cold since it's pretty damn cold out.

The good news is if I jump the starter the car does start!

 

Anything else that doesn't work?
Which connector specifically are you referring to?
What did you do beside the repairs described earlier? The Fuse Box connector did end up being unplugged after all..

Start with the Simple things first, find out why the Starter Relay is not powered when the Key is Turned, that may give you a hint as for the cause of the other issues. Besides that, it's still too early to discount a possibility of the Blown Fuse, for how easy those are to check with a Test Light, there is but a single reason not to check them while at it.

Hope this helps and best of luck!

 

So it's the connector I think 8 pin, can't remember off the top of my head but the one above it is a 3 pin with thick at least 14 or 12 ga wire.

Anyway, so I get power to the ECU but I think i burned out my Theft-deterrent computer because somewhere along the line, I was jumping the wires at the relay, and for whatever reason, the Theft computer won't provide a ground for the starter, but if I manually bypass and jump it I will get a starter crank, and it will start also the gauge cluster lights WILL turn on.

So... I'll hunt a wrecking yard for a new theft computer.

Jumping pin 1 on the orange connector to a ground will give me a start so good news.

 

The fact that the Cluster Goes Out suggest otherwise, even if it is cooked, that won't explain the other issues.

Your reply has changed considerably since I looked last time, I believe you mentioned something about the Cluster coming back up when you shift out of Park, sounds awfully familiar, here is a thread about it, I believe you should be familiar with it..

Go forth and check to make sure that you do have the right Signal from the Neutral Safety Switch, my assumption is that part of the car, Instrument Cluster in particular, gets the Starter Engagement Signal and turns Off all the High Demand items. Check Pin 23 in Junction IK2 as it is described in the thread above, if you have 12V on it, something is wrong with the Neutral Safety Switch, or the Starter Signal Circuit.

Hope this helps and best of luck!

 

So, for future readers, the reason mine didn't work was there is an 8 plug connector below the 3 plug connector behind the battery, on the front bottom of the fuse box in the engine bay. I disconnected it because I was changing the fender liner screw in posts. I completely forgot I disconnected this and only found it after stupid amounts of troubleshooting. However, somewhere along the line of jumping the starter, I must have jumped the power to the ground, causing it to short on the theft deterrent computer. The blue-orange L-O wire goes to the computer and triggers a ground if the car is ok to start, and when I opened the computer as you see in the pics below there was a burned trace. I soldered a wire from the post to the post of the end of the trace and everything is back to normal.

When this wire is blown, you get the dash lights off unless you put the car in drive or reverse. Also the info computer which displays temp outside was out, but the gauges did work.

PIA to fix and I knew it had to be a simple fix... damn.

 

It is quite interesting to see a Theft Deterrent ECU dim the Instrument Cluster along the way, I thought the issue is somewhere in the area, but never expected the ECU itself to be the cause..

Either way, thanks for sharing the solution.

 

Yeah I think it was back-feeding electrical energy or grounding out in specific ways that it shouldn't have been doing. Anyways, all fixed when I ran a wire to the leads on the trace.