Wiring Gremlins... PULLING MY HAIR OUT!

[MeanGreenS13]

FIRST OFF, The problem

1. Ignitor is getting ungodly hot. it will leave burns on your hand if you touch it2. Pin #45 inside the CA ecu is frying on the board. It is a B/R wire which goes directly to the ignition switch.

What we have done...1. Checked continuity on all related HARNESS circuits and pretty much have eliminated the harness as an issue.2. repaired the ecu's (simple fixes_3. removed the turbo timer from the equasion4. looked into possible wiring discrepencies between the VH45(from Q45) and CA18DET Ignitors5. checked continuity from fuse box to brown grey chassis plug that the b/r wire runs to.

What i did tonight...1. for s&gs after my buddy mark left (hes been the wiring man for this project) i wen tout to the car with my multimeter and checked from the B/R wire at the fuse box and then just touched the other probe to the ground strap off the engine to the frame rail... it read .62 ... gonna look more into that tomorrow, not sure if im doing it right as im not much of an electrical buff, but it may be something.

This car has been nothing but a headache, im DETERMINED to get it done but its to the point where im so stressed i cant think straight even at work...

anyone got any ideas besides what we have done

thanks... Phil

[dattodude]

What can make any of these things get super hot?

Can only be wrong wiring, excessive dwell, or bad earths. That's all.

It'll only get hot if it's pulling a lot of current, so something is not earthed properly, or theres a short circuit someplace.

[dattodude]

Pin 45 is the dreaded 'o2 sensor heater' 12V. This is really hard to isolate, unless you've seen it before (preferably on a rainy night after work in an outdoor carpark, while wearing your nice business suit).

Check that the 02 sensor heater still has a good resistance (not short circuit).Check resistance between the outer pins in the 3 pin connector.

I would recommend running the car without the 02 sensor for 15 minutes, and rechecking the pin45 temp, and the temp of the transistor pack.

That 12V line also feeds the AAC, Power Valve solenoid, Turbo Boost Solenoid.

I'd isolate with all of those things disconnected.

[MeanGreenS13]

pin 45? ive got the Pinout right infront of me, its black with red wire goes directly to the ignition switch and to the grey 8pin plug over by the battery tray, as well as to the fuse box on the pass fender.

the only thing i can personally think of is there some kind of chassis harness issue, which i do not understand because the car ran and drove for months before the KA blew.

this car is getting frustrating im beginning to think its never gonna run

[MeanGreenS13]

the black w/ red wire also goes to the 15amp fuse that controls the fuel pump in the fuse box

[JNM240]

My two cents: make sure you have an excellant ground off the battery. When i swapped my CA, the negative battery cable came off the body ground right next to the tray, and even tho it was bolted to the intake manifold, i was having all kinds of weird electrical issues (but mostly stuff cutting out and gauges acting crazy).

[MeanGreenS13]

i ground down each spot where each ground is, i know they are making perfect contact. I relocated my battery to the trunk and using a factory bolt hole i ground down all the paint that the terminal contacts to make sure everything is grounding properly.

I dont think a bad ground could cause the frying of the ecu tho, that doesnt make a whole lot of sense to me... if the ground wasnt touching, wouldnt it jsut do nothing at all?

[JNM240]

I dont think a bad ground could cause the frying of the ecu tho, that doesnt make a whole lot of sense to me... if the ground wasnt touching, wouldnt it jsut do nothing at all?

Not neccessarily. Before i fixed my ground problems, my friend saw the ground strap coming off the cylinder head to firewall glow bright red while i tried starting it once. That tipped me off to a grounding problem.

But like i said, yours may not be a ground issue.

[MeanGreenS13]

i think i may have a short-to-ground somewhere but everything is coming out clean seemingly... its VERY baffling and theres no one really around here that i can get any help from otehr than my buddy makr who has been doing this all with me, and hes even baffled... hes a wiring genious

[mbmbmb23]

Since Q45's have 2 ignitors have we confirmed they are the same part number?...thus interchangeable?

I would go through and redo each and every underhood ground you can...maybe buy one of those grounding kits ...then eliminate that as a possible cause and go from there.

-m

[MeanGreenS13]

the whole thing is becoming a dead beat horse honestly, ive gone over everything 2 and 3 times, we've had the harness wide open 4 or 5 times checking EVERYTHING all the grounds have been gone over.

[MeanGreenS13]

i went over all the grounds once again... anyone at all? someone has to have had similar problems

[mbmbmb23]

Just for the heck of it I'd try to swap out your ignitor for a true CA unit and see if the CA unit heats up in the same way.

Or, you can find someone else with a CA and use your multimeter to take readings from the same points on their car and compare the readings to see if there is a vast discrepencey. Once you locate the place your car reads differently, you can hopefully narrow it down.

[MeanGreenS13]

closest CA to me is DEE and he is in miami, im over 3 1/2 hrs away... ive got 2 ignitors with the same part number out of a 91 Q45...

[mbmbmb23]

You are using the square ignitors with grey metallic heat sincs correct?....Not the diamond shaped black ignitors same as the SR's? Both came on the Q45....just different years.

-m

[ca18detgabby]

think this guy is having the same issue, but with his drop in resistor.......?

zerothread?id=302942

maybe not just the question made me think of this old thread.

[mbmbmb23]

See if this page helps at all with double checking your ignitor wiring.

http://forums2.nicoclub.com/showthread.php?t=51673

[MeanGreenS13]

im using a 91 ignitor so yes, square with heat syncs, i believe is aid that above...

[MeanGreenS13]

Modified by MeanGreenS13 at 3:32 PM 2/24/2008

[niscort]

are you using the euro pinout or the jdm one? they are slightly different, may or may not be relevant.

[MeanGreenS13]

using the pinout in the FSM found here

[float_6969]

Can you fix the trace on the ECU, and then try removing the ignition coil relay? That will determine what portion of the wiring the ground fault is occurring at.

If you remove it and power the car up, that trace SHOULDN'T ever see power if I'm reading the diagram properly. If it gets hot again, then you've got a ground fault in the engine harness. If it doesn't get hot, then we know it's probably in the chassis harness.

[MeanGreenS13]

i could fix the trace, if my soldering skills were that good, its in a place where its really tight and ontop of 2 other traces. I just dont know what to do anymore... ive tried everything and im so broke i cant even afford to eat lunch or dinner 90% of the time. If breakfast wasnt free id probably almost never eat.