99 blazer won't start with avital 4000xl

Hey Guys, I've had an Avital 4000xl remote starter installed in my 1999 Chevy Blazer for over 2 years now. At one point about 6 months ago, I had to replace the ignition switch harness, and ever since then the remote start hasn't worked properly. When I replaced the harness, I made sure to rewire all the connections the same as they were before. The main problem is, when using remote start, the engine will turn, and will even crank, but will immediately turn off. And when the engine cranks for that split second, the starter is still turning. I was told that it's probably that i need to re-learn the tach, but I can't figure out if I'm doing it right or not. I can't find a manual for the 4000xl, but tried these steps: Crank the truck, then hold down valet switch for a few seconds and let go. I'm supposed to hold down the switch until the LED comes on, but I don't have an LED, so I'm not sure. A 556L unit is installed, and I did successfully re-program it just to be sure. The keyless entry still works without a hitch, and the valet mode works as well, but makes the OBDII throw codes shortly after. Sorry this is so long but I wanted to make it as detailed as possible so hopefully someone can help me out. Thanks a lot!! Chris

Isn't there an l.e.d. on the brain box itself?

ok so after fooling with it all last night and some today, I finally figured it out- here's what I did for anyone having the same problem: This should be the same for GM trucks 98-03 I believe, and probly most DEI starters.. (correct me if I'm wrong) The problem was my bypass module and tach wire not wired correctly. The tach wire is a white wire coming from the ignition coil- originally the RS was wired up to a white wire coming from the computer. Might be the same, but wasn't working for me. My bypass module was wired up to the wrong ground wire- you have to use the passlock ground wire, NOT chassis ground. This is a small ORANGE / black wire in the ignition harness. I made sure, after rewiring those, that I reprogrammed the bypass module and relearned the tach. One other problem I had that I fixed was that even when the remote start worked, it made the OBDII throw codes. Come to find out, the 2nd ignition output from the RS was wired to the wrong wire in the truck- you MUST wire a 2nd ignition to the small white wire in the ignition harness. If not, it will throw codes, and eventually trash your tranny, because the solenoids in the tranny all run off these wires too. I had to get a complete tranny rebuild earlier this year, and I'm pretty sure now that this incorrect wiring was why. Now it starts up perfect and NO CODES.. :) :) :)

oh and btw.. if anyone owns a 4000xl you'll find that manuals and info for them are IMPOSSIBLE to find.. After a bunch of searching I figured out something that helped: First, the AviStart 4000 and the Avital/AviStart 4000XL are two VERY different systems- don't get the install guide or any info for the 4000 thinking they're the same. However, the 4000XL and the 4100 ARE the exact same. The only difference is the XL shipped with only one remote, whereas the 4100 shipped with two. I had a lot more luck finding info whilst searching for 4100

Wow who originally installed the first one? That second ignition thing is a very well known thing.A DMM is a beautiful thing.

MECP Advanced Installer Certified.