89 Electrical Problem

[ob1murry]

Hey guys,

So I made a pretty dumb mistake the other day. We have an 89 that has been sitting for a couple of months. We currently have 5 cars, and I was too deep in other projects to get to this one. Well, I finished my other project enough to get it out of the garage. The other night, I went to move the Supra into the garage, and found that no surprise, it had a dead battery. I went and grabbed one of the batteries I had sitting in the garage from the other car, and like a moron, in the darkness, I hooked the battery in the Supra up backwards.

The headlights and hazards work when hooked up to a good battery, the dome lights work, but the door sensors do not appear to be working, it doesn't even attempt to crank, tail lights, fog lights, dash lights, warning lights, climate control, basically nothing else works right now.

I'm hoping we can just skip over the "What an idiot!" and "Rookie Mistake" stuff, and that I can get some help from people alot more familiar with this platform than I am.

I have started going over all of the simple stuff so far, checking all the fuses (haven't found any blow ones yet, but replacing them all anyway), but so far I'm not very hopeful that this is going to solve the issue. Can you guys help me figure what I might be able to do to start narrowing down which components might be bad, and the best way to proceed.

First things first, I need to figure out why all of the interior seems to have blown out. It can't be related solely to the ignition, because the door locks and door sensors don't work. Does the ECU control any of these functions?

I'd really appreciate any help anyone can give me. Like I said, I'm not helpless when it comes to this stuff, but this is my first time working with this platform.

Thanks

 

[hvyman]

check all the big fuses in the engine bay. and the fusable link

 

[3p141592654]

More info here. Hopefully just fusible links, but be prepared for the worse ...

Start by checking the battery and alternator links. These are dealer only parts as far as I know.



http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=036

 

[ob1murry]

You just saved me hours. I had already replaced all the fuses under the hood, but I forgot about the link because I didn't have one anywhere in the garage.

Made a run to autozone to pick one up, and everything seems to up and running now, and it at least tried to crank over, but the spare battery I had was too low to get it going.

Thank You

 

[ob1murry]

Alright, well, as expected, it cranks but won't start.

I have a couple of questions here.

1.) If this turns out to be the fuel pump, does an aftermarket fuel pump like a Walbro require an AFPR, or is the stock FPR capable of handling it? I search around, but didn't see any mention of an AFPR, which leads me to believe it is fine without one, just want to make sure.

2.) No warning lights on dash when the key is moved to on, which certainly seems like an issue with the ECU. I'll continue checking the fuses once it stops raining and I can get it done, just to make sure. Assuming that the ECU is bad, is there a good way to test it aside from just checking for power at the ECU? Are there any good alternatives for the ECU that are not complete standalone or piggy back units like the AEM or E-Manage? I'm thinking something like dsmlink/ecmlink for DSMs/EVOs.

3.) What is the best way to test the ignitor so that I can ensure it is getting spark? Same for the injector resistor?

 

[3p141592654]

If you have no CEL, then you have no spark or fuel either. No need to check until you get the CEL working.

Hopefully you noticed that there are two fusible links (AM1 AM2) in the left kick panel JB. Did you check those? They are rather important for the car to run.

 

[ob1murry]

If you have no CEL, then you have no spark or fuel either. No need to check until you get the CEL working.

Hopefully you noticed that there are two fusible links (AM1 AM2) in the left kick panel JB. Did you check those? They are rather important for the car to run.

Wow, no I did not. I pulled the cover off and took a look at it, but our garage is rather narrow (too narrow for my fat ass to be able to manipulate my way under the dash to see in there), and it's been raining for the last several days, so I have not been able to push it out and work on it outside where there is more room.

I will be sure to check them out and then let you know.

I appreciate the help on what are really rather basic questions for you guys at this point.

Thanks

 

[3p141592654]

Sorry, the AM1/AM2 FLs are under the hood. No need to get into the left kick panel JB. although there are fuses behind that kick panel that I assume you checked already.

http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=18

 

[ob1murry]

Alright, the CEL is back on now. One of the fuses was blown, but not on top, more to the side, which made it very difficult to see.

The diagnostics returned codes 14 and 51.

Both of these codes list the ECU as a problem area.

Should I even bother trying to test the ignitor, or just go ahead and assume it is the ECU? I'll check the fuses again to make sure none of them blew out after checking them before, but is raining again.

It is clearly getting fuel, you can smell it, the car keeps coming very close to starting, and even feels like it starts for about a second, before it just dies.

 

[3p141592654]

Its less likely to be the ECU. It is well protected against reverse polarity, which is why the fuse blew. The igniter should have been isolated from the chaos by the ignition switch, which I assume was off. I would check the igniter first though since code 14 is an ignition issue usually. Code 51 may just be from having the AC turned on. Code 51 will not cause a no-start.

 

[ob1murry]

Alright, so I started trying to test the igniter following the procedure outlined below, but I have some questions.

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=IG&P=15

Step 1 checks out OK (Aside from only seeing 9 volts, which is due to the battery being low and only putting out 9V), but Step 2 I am having trouble with.

It's intermittent, but I believe that is a problem with keeping the wire connected properly. What should we see when testing this though? We should just see a quick change in voltage like it is momentarily firing? Does the 3V battery get grounded to the igniter?

Edit:

Just to be clear, I did have my girlfriend trying to turnover the car when I had reverse the terminals, so no, the ignition was not off when it happened.

 

[3p141592654]

Ughh. With the IGSW on, the only fuse protecting the igniter is the 30A FL. You may have fried it.

 

[ob1murry]

Alright, I know it's been a few days, but i finally got around to finishing testing the igniter per the instructions.

Everything checked out according to what the page says I should see, although it does not give any indication of what an acceptable resistance to see would be, so I have no idea if it is still fried and the resistance is way higher than normal. Is it possible to pass those checks and still have it be bad?

If power is making it to the igniter, which Step 1 would suggest that it certainly is, and the igniter itself checks out, it must mean the problem exists with the coils, wires, plugs, right? Is there any specific relay/fuse I should check out to make sure it did not blow again?

Maybe I need to revisit my claim that I was sure it was getting fuel? Seems unlikely though since the diagnostic code was specifically for the ignition.

 

[ob1murry]

Alright, I have run through the entire TSRM ignition system, and everything has checked out.

The only thing I can think of yet is to check the continuity of the IGF wire from the igniter to the ECU to make sure there are no breaks.

Is there any way to test that the IGF signal is being sent from the igniter? I searched around alot, but everything I found was just people asking how to simulate it to a megasquirt on a JZ swap, and the consensus seemed to be "You can't..."

Is the IGF dependent on seeing energy released by the coils, that a bad coil could cause the issue? Should this code even prevent the car from starting? All the research seemed to point to people who had this issue, but the car was still driving. Is it possible that something else is causing the no-start, and this is just a second issue?

I don't have a problem spending money to but the necessary parts to fix it, but I'll obviously be mildly annoyed if I just have to eat it and buy the components individually and replace them until I find the one that is bad.

 

[ob1murry]

Really? No one has any more information?

Can we start with the simplest question, which is, should code 14 cause a no start? Because based on what I have read, the answer is no, and that the car should still start, but the ignition timing might get funny and misfire since the ECU can't tell that the ignition is firing.

 

[3p141592654]

Remove the CPS from the engine but leave it connected.

Hook up a sparkplug to one of the ignition wires and ground the plug body with a piece of wire or whatever works for you.

Turn the ignition on and spin the cps by hand. You should see some healthy sparks at the plug. No sparks, means you don't have a functioning ignition system.