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Update: the issue has to be from the ignition to the fuse box. I can take a hot wire and touch it to the prong on the left side of the fuse and it will start. Still NO HOT ON START from ignition switch. 🤷
I'm starting to think there maybe some corrosion inside the fuse box as the prongs(where the two main harnesses connect to the back of the fuse box) was badly corroded. I tried to clean them and that was when I was able to start the truck by jumping the left prong for F21. After trying to diagnose any issues with the ignition switch(no luck, btw), I am now unable to start the truck up at F21. I plan on going to get another fuse box as soon as the weather clears up. Have some bad storms rolling through GA tomorrow.
I do want to thank you for guiding me on the diagnosing process.
I never had to replace the ignition switch on my old '97 during the time I owned it (same configuration as yours) so I couldn't say exactly whether the following applies. Maybe one of the other owners who has done it can comment better.
I do recall that my old 89 SHO needed an ignition switch so I replaced it in the O'Reilly's parking lot on the way home. No crank. Finally figured out that there was a gear arrangement in the mechanical linkage between the ignition cylinder and the switch and I was off a couple of teeth on that gear so that the switch didn't rotate far enough to "make" the switch when the key cylinder was turned all the way to start. I readjusted that gear engagement and it worked properly. I have no idea whether or not the pickup has that same type of mechanism.
I really don't see a need for a complete fusebox, especially without having done any pinpoint testing to see if it's actually bad.
Last edited by projectSHO89; 02-05-2020 at 08:00 PM.
I never had to replace the ignition switch on my old '97 during the time I owned it (same configuration as yours) so I couldn't say exactly whether the following applies. Maybe one of the other owners who has done it can comment better.
I do recall that my old 89 SHO needed an ignition switch so I replaced it in the O'Reilly's parking lot on the way home. No crank. Finally figured out that there was a gear arrangement in the mechanical linkage between the ignition cylinder and the switch and I was off a couple of teeth on that gear so that the switch didn't rotate far enough to "make" the switch when the key cylinder was turned all the way to start. I readjusted that gear engagement and it worked properly. I have no idea whether or not the pickup has that same type of mechanism.
I really don't see a need for a complete fusebox, especially without having done any pinpoint testing to see if it's actually bad.
While I was doing some testing with the ignition switch, I decided to test to see if the switch was no being triggered all the way in start. The "guide" inside the column for the ignition switch "pushes" all the way to the end as far as it can physically go and there is no gap. Same with the switch. So, I don't think that it's an issue with the switch itself, which is why I decided to take a gander at the fuse box. I removed the whole thing(2 bolts and 2 nuts along with the 3 connectors to the GEM module and the 2 wiring harness connectors that plug directly into the fuse box itself). It was actually pretty simple to remove, but when I had it out I examined it and it had green color corrosion on 3/4 of the prongs on the fuse box itself where the 2 wiring harnesses connect directly to it.
Taking a BIG step backwards. The truck had been sitting for 6 years and I when I got the truck I went ahead and replaced the windshield. They told me that the previous windshield was leaking on both passenger and driver side.
I had to replace the ECM(PCM on passenger side under dash/harness connector is next to battery) due to it not sending out the ground signals for cylinders 1/2/3 and 7 due to the same corrosion issue that I found in the fuse box. 🤷
I don't know how to pinpoint check the fuse box to be honest. The only thing I know to do is buy one, stick it in, and hope it works. If it doesn't, then I need to find the start interrupt relay and/or RAP module and possibly replace both of them.
So the fuse box didn't help. My battery was also draining for some reason, maybe that'll fix that. But I'm not sure what's going on. I guess it's either the start interrupt relay or the rap module.
Parts off of a 1997 works great with my truck tho. I'm not sure what else to do. I read somewhere that someone was also having the same issue and wound up replacing the starter. If I can find the rap and start interrupt relay, I can just replace both of them too. It's gotta be something keeping it from acting right. Still NO hot in Start and still can't cross it out at the fuse box anymore.
Not that I have found. Doesn't have any modifications to the wiring or any thing that doesn't look normal. I still would like to know where the start interrupt relay is. Maybe even the RAP module...
Where first you had one problem, now you have two.
1. No HOT IN START at fuse F21. The starter relay and RAP module, if even installed, cannot cause this problem. Fix this first! It's a problem with your ignition switch, its adjustment, or the wiring to the fusebox.
2. No activation if power injected at F21. Fix #1 first....
Put the wrenches and screwdrivers away for a bit. Replacing stuff is getting you nowhere.
Don't take the following the wrong way, it's not meant to be critical... Your enthusiasm to poke around and replace stuff is noted, but there is one critical set of skills that you seem to not yet have gotten to. What's really needed is to add a multi-meter and its usage to your toolbox. That tool will allow you to check the continuity of circuit paths that don't have power applied to them and will supplement your test light to check for circuit activity and functions. It can also help you avoid going down rabbit trails of guessing and replacing due to not realizing how circuits are supposed to work. I'd encourage you to pick up a multi-meter (you can buy a "good enough" meter for about $20-40. get one with a continuity beeper) and then spend some time over at YouTube University learning how to make basic voltage, resistance, and continuity checks. Let us know if you decide to do that and we can advance.
Test THROUGH the ignition switch to see if you have continuity through the switch between the B4 and STA terminals in START position. Note: Disconnect battery negative terminal FIRST.
As projectSHO89 has said, check for continuity between STA and B4 with the selector pushed into the START position. If you don't have continuity, then your switch isn't good and needs to be replaced.
If you do have continuity, then reconnect the ground to the battery and check the B4 pin on the harness for 12V. It should be hot all the time. If there's not 12V, then the fuse supplying the circuit may be burnt out.
Wasn't getting continuity with STA/B4 on brand new ignition switch in start position that I just bought a couple days ago. I tested the one I bought earlier this month and I had continuity. So, I had to; a) put the earlier ignition switch back on it and b) adjust the Neutral Safety Switch.
Truck starts fine now. Thank you so much for the diagram.
And thank you everyone for your help with this. Now I can get some tires and and fix a few cosmetics and then get it inspected. 😁
02-05-2020, 03:49 PM
