2008 LT2 2500 4WD, no crank, no run

gordr

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Hello. New here, but I've been on some other forums for years. I just bought a 2008 3/4 ton 4X4 Suburban from Canadian gov't surplus. Was formerly an RCMP unit. Got a good deal on it, as it's non-runner.

Put the key in the ignition (got 2 keys and fobs), turn it one notch, gauges and dash warning lights illuminate. All lamps, as far as I know. Wait 10 seconds or so, and all lamps except the "engine icon" go out. So far, that's normal, right? All lamps come on for bulb-check function, then all go out. Engine lamp remains on because engine has not started.

Turn key another notch to crank position, and zero. No crank, no click, no lights. Nothing.

What I know so far: vehicle had a remote start (after market) on it, removed before I got it. Also had all the usual cop gear, mostly removed. (they left part of the alternate headlight flasher, which I removed).

Batteries (2) are fully charged. Starter will crank engine fine if jumped at the solenoid, or if I take the cover off the starter relay and close it manually. I squirted some gasoline into the intake manifold via a vacuum port, and with the ignition switch on, closed the starter relay by hand and the engine started, and ran very briefly. So the ignition system works, at least while cranking. I can't be certain it works when starter is disengaged.

Fuel pump does not run with ignition turned on, but will run if fuel pump relay is jumpered, and pressurizes fuel rail OK. Cranking engine with fuel pump relay jumpered will not start it. Conclusion: injectors are not firing.

Been doing lots of reading; thought it might be the anti-theft device. Security light comes on during bulb check, then goes out. Supposedly, if anti-theft system has triggered, the security light should flash. Tried the ten and thirty minute "security re-learn procedures", no joy.

I'm away at work for 2 weeks, and the dead 'burb is at home, but I will archive any responses, and try them when I go home.

I like my 'burbs; also have '96 with 6.5 Diesel, '97 with 350 Vortec, and an '88 with 6.2 Diesel. All 3/4 ton 4X4.
 
A guess would be ignition switch but I assume you checked the fuse box for any blown or missing fuses or relays?
 
No fuses or relays missing. Well, there is an empty fuse site for "heated running board", but i doubt that's relevant. Mind you, a heated tailgate would make for easier pushing in cold weather.

I am wondering about the ignition switch. Three wires leading from were tapped into for the purpose of installing the remote-start device. One of those is always hot, presumably battery feed. One becomes hot with the ignition on, and goes cold in the crank position. Presumably that's accessories. The third wire indicates nothing using a test light, in any switch position, and connecting it to either hot or ground does nothing, either. I did check the neutral safety switch, and bridging it does nothing, either.

The ignition switch and neutral safety both feed into a large black box under the steering column with multiple multi-pin plugs on it. I assume that is the body control module? I wonder if a short to ground occurred as the remote-start was being disconnected, and burned out something in that black box? It is indeed black.
 
Have you tried a search for the wiring diagram on the internet?
 
I have searched, and haven't been able to locate one, except possibly at sites where you have to pay for the service. I wouldn't mind paying a set sum for a wiring diagram; not all that crazy about paying to join a site.

Any suggestions about a good place to look? I will check in with a dealer this week.
 
Update: problem solved, the struck starts, runs, and drives fine.

How I did it: 1. Signed up and got a library card from my local public library. That got me access to a number of online databases that require a username and password to enter. Went to the "auto repair" database (provided by www.ebsconet.com) and downloaded about 8 pages of wiring diagrams as .pdf's.

2. Bought a scan tool, and read the codes. Got P0615, which denotes a problem with the start relay circuit. The PCM was not "seeing" the crank relay.

3. Used the wiring diagram to determine which pin on the PCM provided the signal to the crank relay; it turned out to be pin 52 on J1. With the PCM fully out of the vehicle, I put a jumper into pin 52 of the cable going to J1, and applied 12 volts. Nothing happened; it should have energized the relay, and cranked the engine.

4. Followed the harness from J1 back to the main fuse box, where the crank relay lives. There was some black tape on it, and a wire running from there to an obviously aftermarket alarm horn bolted to the alternator bracket. Stripped off the black tape, and found the wire from pin 52 of J1, yellow/black tracer, had been cut, and new wires soldered to the severed ends. Those two wires were bundled along with the one to the alarm horn, and went towards the firewall, where they just ended, cut off. Must have gone to an aftermarket alarm/command start interface box, removed by the mechanics at the police garage (ex RCMP vehicle).

5. Found a small piece of wire, and rejoined the severed yellow/black wire, soldering and heat-shrinking the splice.

6. Reinstalled the PCM, turned the key, and the engine cranked and fired, and quit. Tried again, and it started up and stayed running. Drove it about a half mile, everything seems OK.

Hope that this helps somebody else.
 
Nice job of troubleshooting and repairing the problem, man. Your tenacity paid off. I'm glad to hear that it's up and running for you. Now, go and enjoy it.
 
Nice job of troubleshooting and repairing the problem, man. Your tenacity paid off. I'm glad to hear that it's up and running for you. Now, go and enjoy it.

Thanks. I plan to do just that. I followed up because maybe that information will be of use to some other reader. All too often on forums like this, a thread can run on and on, and you never learn whether or not the original poster solved their problem, nor how.
 
That's true, man. I'm a member of several forums and I'd love to have a dollar for every time someone has had a problem, gotten suggestions about how to solve it and never return to let anyone know. Drives me nuts!!
 
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