4age Silvertop wiring issue Options

[lagos]

I've been helping blackscarlet get her swap running at it seems we ran into a wiring related issue and the car will not start. The harness was original done by DrTweak many years ago but the swap was never completed and the car sat for a while. Maybe a few 4age gurus on here can point us in the right direction.

Here are the issues.
1. the car will not crank
2. the srs warning light is behaving oddly and staying on even after the key is out of the ignition.

I feel like there is a grounding issue going on here. On the 3sgte there is normally a ground wire from the main harness to the back of the intake manifold that provides a ground for the injectors and a few other things in the EFI circuit. I had blacscarlet take a look under the car but she couldn't find any grounding wires on the back of the 4age intake manifold ... is it located elsewhere or handled differently on this engine? I don't have a proper wiring diagram for this motor, just the ones for the car.

The cranking issue could be caused by an alarm that is installed. Figuring this, I bypassed the starter relay and supplied my own 12v to engage the starter. The engine cranked without problems but would not fire.
Next I tested to see if we had spark, and it seems that we do not.
I went on to test the injector harness clips for power, and they did indeed have it, along with the main power wire that feeds power to the coil.

I still feel like this is a grounding issue due to the odd srs behavior, or in the worst case, a problem with the wiring harness conversion.

Anyone got an idea as to what could be going on?

[PhoenixTech]

If you think there's an issue with the harness, send it back and we'll go through it. All of our harnesses have a lifetime warranty. IF there is a problem, we will repair it and ship it back to you, covering shipping both ways.

As for the lack of spark. What igniter are you running? If you don't have the original Silvertop igniter, you can run a 201 igniter from a 4Runner.

Grounds. make sure the engine is also properly grounded to the chassis. There is one main ground on the engine harness that provides the ground for the ECU, and the necessary sensors that need it...injectors are not one of them. Injectors have a power source, and a signal wire. No ground wires.

SRS light....have you removed your steering wheel at all, with the clock spring? typically, the SRS light will stay on if the clockspring in the steering wheel is bad, or if one of the sensors on the front of the car used to indicate an impact and blow the airbag has been tampered with.

Lack of starting. remove, or disable your car alarm completely and see if that changes anything. This is a very common problem on Supras and SC's with their factory alarms when a swap is done.

-Cam, Tweak'd Performance

[lagos]

As for the lack of spark. What igniter are you running? If you don't have the original Silvertop igniter, you can run a 201 igniter from a 4Runner.

I'm not sure and will have to check (its not my car, just someones that I'm helping), but from my personal experience an incorrect igniter wouldn't prevent the car from starting. The car would still start but have trouble reving over 5k or so.

Grounds. make sure the engine is also properly grounded to the chassis.

There is one main ground on the engine harness that provides the ground for the ECU

, and the necessary sensors that need it...injectors are not one of them. Injectors have a power source, and a signal wire. No ground wires.

Where is this ecu ground located? On the 3s this ground is at the back of the intake manifold but it doesn't seem to be the case on the silvertop.

SRS light....have you removed your steering wheel at all, with the clock spring? typically, the SRS light will stay on if the clockspring in the steering wheel is bad, or if one of the sensors on the front of the car used to indicate an impact and blow the airbag has been tampered with.

The factory wheel and clock spring are all in place. The srs light behaves strangely, staying on even when the ignition is off. I have seen this on a few swaps before and its always been related to a wiring or grounding issue.

Lack of starting. remove, or disable your car alarm completely and see if that changes anything. This is a very common problem on Supras and SC's with their factory alarms when a swap is done.

The alarm could very well be the cause of lack of cranking, but it shouldn't affect the actual starting of the vehicle if the starter is engaged manually. I did remove the alarm and bypassed the starter relay but still had no spark.

[PhoenixTech]

The ground on the engine harness is the same style as a 3S...ring terminals with a handful of wires crimped onto it. normally they come out of the harness near the distributor and ECT sensors on a 20V

[blackscarlet]

I had a few small wiring issues in the relay box. I do have spark now. The SRS light is also off now. I checked the voltage on almost every harness plug and everything is getting power. I believe the issue is my fuel pump which i will be replacing this weekend. I am unable to hear the pump running at all and the car has been sitting for almost a decade. Thanks for the responses and I'll let you know if the fuel pump was the only issue this weekend.

PS I do have the 201 4 runner igniter as well.

This post has been edited by blackscarlet: Jun 5, 2012 - 7:54 AM

[PhoenixTech]

I had a few small wiring issues in the relay box. I do have spark now. The SRS light is also off now. I checked the voltage on almost every harness plug and everything is getting power. I believe the issue is my fuel pump which i will be replacing this weekend. I am unable to hear the pump running at all and the car has been sitting for almost a decade. Thanks for the responses and I'll let you know if the fuel pump was the only issue this weekend.

PS I do have the 201 4 runner igniter as well.

Sounds good! Also, if you fuel pump does not turn on while cranking, check your circuit opening relay under the dash next to your ECU.

[lagos]

I had a few small wiring issues in the relay box. I do have spark now. The SRS light is also off now. I checked the voltage on almost every harness plug and everything is getting power. I believe the issue is my fuel pump which i will be replacing this weekend. I am unable to hear the pump running at all and the car has been sitting for almost a decade. Thanks for the responses and I'll let you know if the fuel pump was the only issue this weekend.

PS I do have the 201 4 runner igniter as well.

Sounds good! Also, if you fuel pump does not turn on while cranking, check your circuit opening relay under the dash next to your ECU.

The pump is not coming on with b+ and fp jumpered, yet there is power at the fuel pump harness plug... So the current diagnosis leads to a bad fuel pump that died from the car sitting for a long time. I will verify the COR after we are able to actually start the car to make sure it can also start without bridging the diagnostic box.

The rest of the issues appear to be from EA1 not being fully secured into place, causing all kinds of electrical oddness with lack of spark and srs warning light going crazy. So, so far the harness appears to be in good shape. We will keep this thread updated once the new pump arrives!

This post has been edited by lagos: Jun 5, 2012 - 10:24 AM

[PhoenixTech]

Yes, please let me know if you have any other questions or concerns. I'll try and pay attention to this thread, if I'm MIA, just yell at me on Facebook, or email me at cam@tweakdperformance.com

[blackscarlet]

Lagos helped me replace the fuel pump yesterday and the car is running now.. Still have some issues to work out but at this point I believe everything with the wiring harness is good. The short list: I need to correctly hook up all the vacuum lines, drill holes and mount the power steering reservoir, remove the alarm, and have an exhaust made.. plus a some odds and ends...

But Thanks for the help and Thanks Tweak for doing the wiring harness (6 years ago lol). I will definitely post some updates...

Wasn't sure I'd ever see the day of this car running

[PhoenixTech]

Good deal. Also, you might want to throw a new fuel filter on there as well if you haven't already. I had a similar problem with my Civic when I turbo'd that car. Fuel filter was so clogged it wasn't letting enough fuel to the engine and was running super lean and had hiccups all over the RPM band.