# GMC PassLock troubles??



## blue98gmc (Mar 15, 2005)

I plow with a 98 GMC 2500 Club Coupe, equipped with an 8’ Fisher MM1 plow rig. (Belt driven hydraulic pump, but solenoid operated lift and angle function.) My problem started when I had a remote starter installed around Christmas. It worked fine for several starts, but then it would just crank and not start. Even using the key, no dice. The installer told me (at 5:00 AM in a blizzard!) to shut everything off, and to leave the key in the “on” position for 10 minutes. He thought it was a problem with the factory-installed anti-theft device, (Pass-Lock, maybe?) and this was the “reset” routine. I did that, it started fine, and ran perfectly for the rest of the storm. Since then, the problem keeps popping up occasionally. He’s changed the entire remote starter out with no improvement. Finally, I had him remove it entirely , but the problem is still there!!! Now, I can get it to start alright, but if I drive off before it’s thoroughly warmed up, the antilock idiot light comes on, then the brake one, then both with the “security” light, and some sounds like the 4X4 solenoids cycling and boom! It’s dead. Oh yeah, the clock resets to 1:00 as well. I can do the 10 minute reset and it’ll restart, but again, if it’s not completely warm, it quits again. The maddening thing is that it doesn’t happen all the time. Does anyone have any ideas? ⨪


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## Bad Luck (Sep 30, 2004)

The guy might not have put a Passlock bypass unit in the truck. It's a must for any alarm/remote start put into a GM vehicle with passlock. If he didn't, it's possible he either "jumped" the system somehow and screwed something up, or did work until the system figured out what was going on and went bananna's. Before having someone else look at it, check all your fuses, especially any underhood. The peek under the dash and make sure the guy completely removed the unit. If you have no luck there, I'd get the truck to a dealership as I would trust no one else with a factory anti-theft device. 

Good luck. Post results.


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## JMR (Feb 24, 2003)

I would suspect a bad ignition switch HARNESS or ignition switch. We have seen some damaged ignition switch harnesses from remote start installations causing the exact problem you are describing.


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## blue98gmc (Mar 15, 2005)

*...more info, JMR?*

Thanks for the quick response, JMR. Could you elaborate on what KIND of damage you've seen, and what I might look for on my own? I'm kind of reluctant to blindly put my faith in the dealer, (we've ALL been burned somewhere along the line), and I don't want to automatically assume the installer did the damage without some proof, either. Is what you've seen visible to the naked eye, of does it require using a multimeter or other electrical troubleshooting equipment?

Summer's coming, and I sure don't want to have one of these incidents while towing the boat!

Thanks again....................


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## JMR (Feb 24, 2003)

To test: 

Measure the voltage at the yellow wire in the 3 wire connector at the lock cylinder case. It must be over 5 volts. 

With the ignition switch in the cranking position the voltage must be around 2.5 VDC it will vary slightly because of different pass lock sensor resistenances. 

If you don't get these values replace the harness.


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## blue98gmc (Mar 15, 2005)

*Thanks again, JMR*

thanks, I'll do a little detective work and let you know what I find out. Too bad NE is so far from MA, or I'd bring it to your shop!!


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## blue98gmc (Mar 15, 2005)

*Hey JMR..further clues........*



JMR said:


> I would suspect a bad ignition switch HARNESS or ignition switch. We have seen some damaged ignition switch harnesses from remote start installations causing the exact problem you are describing.


JMR, I'd be curious to get your thoughts on the latest developments. I haven't gone to the dealer yet, 'cause we have had a seemingly enless string of storms, and I've got to have the truck available, wounded or not. Anyway, I went out last evening and warmed it up thoroughly, drove it across the street to a parking lot where it promptly died again. I waited for the 10 minute reset, started it up, backed up 50-60 feet, put it in drive and started to accelerate about as I would going down the road. (I'm still in the lot across the street now) BOOM, it dies again. BUT, I noticed that the headlights, not the plowlights, were on. I got out, pulled the electrical connection for the plow, and put it on and off several times, in case there was any corrosion or crud on the connections. The plow lights came back on, of course, I got in, started it right up, and drove down to Rte 1 (5 or so miles) to get gas and back with no problems whatsoever.

What do you make of that? It's almost as if any little stray draw or voltage variation causes the PassLock to shut everything down. I wonder if the damn thing can just be completely disabled by a dealer................might be the best solution. What do you think?


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