Strange Starting Problem

[Sundown94]

Back in May, I had a problem where I would turn the key but the truck would not start. The battery was fine, the lights all worked, the dash lit up, etc. It just wouldn't start. Had it towed to the shop and when we got there, it magically started up as soon as we turned the key. The mechanic said he scanned for codes anyway and that everything seemed to indicate that I needed a new ignition switch, so we put one in.

Last night (about six months later now), I had a similar situation where the the truck would not start. So my wife picked me up (I just locked the doors and left the truck there) and this morning I drove back to the truck with plans to call AAA so that it could be towed to the shop. BUT, I put the key in and it started right up. So I drove it to the shop and the mechanic is going to try reading codes again.

Here is what is similar (IMO) to both cases: 1) the truck decides to start after I leave it alone for some period of time...so in the first case, it started after it was towed to the shop, while in the second case it started after I left it in the parking lot over night. 2) in both cases, I had only started the truck and drove it a short distance (about 1 mile/5 minutes) and then I had the problem starting it afterwards.

Is this really a problem with the ignition switch, or is it related to something else such as the security system? I mean, if it was the ignition switch, why would it magically start after just sitting there untouched over night? Instead, I am wondering if the security system encountered a problem and has some kind of reset period (like maybe an hour needs to go by and then it resets itself or something). The battery was definitely not dead (and just to be sure, I did try jump starting the truck before I gave up last night). Any ideas???

Thanks!
Steve-

[twr]

hi check the voltage down at the starter when it happens, have someone turn the key over and check the starter with a voltmeter or a test light. I know alot of hummers had problems with the ingition switch. Maybe the neutral switch or the starter itself. Hope this helps.

[Hellz]

shifter might not have been fully in the park slot. i had this happen to me before. i turned the key to release the shifter and moved it out and back into park. started right up after that.

[HUMTECH]

My guess is the starter. you can check for voltage at the starter or next time it wont start, hit the starter with a hammer, if it starts you need to swap it out

[Sundown94]

Thanks for the suggestions so far. As an update, the truck is now sitting at the shop and no longer starts, no matter how long we wait (eliminating my thought that waiting might be correcting the problem). Apparently I got lucky when it started one more time which allowed me to drive it over to the mechanic. He has not been able to start it since then. But he attached his scanner and said that it is coming up with some kind of communications errors (can't remember what they are) and other codes that make him think there is something wrong with its ability to read my keys. They are not the codes that are related to ignition switch problems. Whatever they are, he said the problem is computer related and needs to be towed over to the dealer for further testing because he does not have the appropriate equipment.

If there was a problem with the starter (which was just replaced last year due to a problem with the gear staying engaged for a split second too long and making a horrible sound), would the computer produce "communication error" codes? Or do you think he is right that there is something wrong with my keys/security system?
Thanks!
Steve-

[HUMTECH]

Sounds like something is bringing the class 2 line down. Do you have an aftermarket remote starter installed? If ya do check for a wiire splice behind the data link connector(where the scan tool plugs in) if there is a splice there disconnect it and see what happens

[Sundown94]

Wow, thank you for the advice Humtech!! This seems to be the most promising so far because indeed I do have an aftermarket remote starter installed (I bought the H2 one-year used and it was installed by the previous owner, so not sure what kind it is or where it is located). If I find the splice you are talking about and then disconnect it, does this indicate that my remote starter went bad? Could it actually be a problem with the splice (maybe the wires broke)? I will give this info to the mechanic since the truck is still sitting at his shop when I drove by today.

Thanks again!
Steve-

[HUMTECH]

Most starters get spliced into the data line to run various other functions such as door locks. If the module goes bad and sends voltage spikes or grounds the data line it can cause various problems with the truck

[HumminNBoatin']

I could not agree more with Humtech. When I was in High School 10 years ago I worked for Circuit City installing these remote starters. I can tell you they are nothing but problems after the first year or 2.

At least once a week we where removing remote starts from cars because of various problems.

[Sundown94]

OK, here's the latest update. My mechanic said that he disconnected my remote starter from the "purple wire" behind the DLC connector. (I know there wasn't any mention in this thread that the wire was purple, but I found it while searching in other threads for other possible causes of my problem.) Anyway, the truck still isn't starting and has now been stuck at the shop for over two weeks. The mechanic also said something about checking the ignition switch to see if it was sending a "start" signal, and apparently it is. He said he checked some relays too. Does anyone have anymore ideas on this? Humtech?
Thanks!
Steve-

[HUMTECH]

well if the starter relay is energizing and there is no power at the starter s terminal you have an open in the start circuit between the relay and the starter. If the starter relay is not energizing you have an open circuit between the ign switch and the relay

[Sundown94]

Thanks Humtech! I will give the info to my mechanic and report back on how it goes. Honestly though, at this point I am also thinking about having my truck towed over to the local GM dealership to see if they are better equiped to figure out the problem. Not sure what yo and others here think of this idea (good or bad?).

[Sundown94]

Here's another update. I spoke to my mechanic about the possibility of an "open circuit" and he said he has tested for that. The newest information is that his volt meter is reading different voltages at the starter solenoid...all of them low enough that the solenoid won't work. For example, some of his readings were around 8 volts. But the battery is very healthy and -- on few occasions -- the truck started just fine. What could be causing the voltage going to the starter to fluctuate? Is it a short? Can it be the remote starter (can it interfere with the juice that goes to the starter)? This is getting extremely frustrating!

[Olfart]

Check all the crimped connector ends at the starter and solenoid. Could be loose or have corrosion from moisture which would add enough resostance to cause the voltage drop to 8V under starter load. Better yet...replace them and make sure that all conections in the starter circuit are clean and tight.

[Sundown94]

Thanks Olfart! Does anyone have any wiring diagrams, or does anyone know where all of the connections are located between the ignition switch in the steering column and the solenoid on the starter? I ask because I am sure it is not one long solid wire...there are probably several connectors along the way. This may sound rediculous, but I am actually thinking of taking a day off from work so that I can spend it with the mechanic trouble shooting this problem. At this point, it will be at his shop for a month (this Friday) and the possibility for bad weather is increasing every day as we head into the depths of winter, so I really would like to get the H2 back and put my '94 Z-28 (now a classic) back in my garage.

[HUMTECH]

[HUMTECH]

Check connections for remote start in ignition switch harness, could be a bad connection causing your 4v voltage drop or even the remote start module pulling the circuit down via a bad ground or internal short