lockman

2009 Chevrolet Express 2500 Cargo Van I'm rigging out for work.
About 3 months ago I had a Clifford Alarm system with remote start installed. The alarm system required one of my two keys to be installed into a reader under the dash so it would start remotely. The system worked fine.
About 1 month ago I installed a secondary battery connected to a 5000 watt inverter in the back of the van with an isolator next to the primary battery under the hood. Per the isolator manufactures instructions, I hooked a switched wire from under the dash to the isolator for the required excitation voltage for the alternator and rerouted the charge wire going to the battery from the alternator to the isolator from the alternator. I tried it out and found that the alternator did not have a way to sense battery voltage so there was barely 13 volts comming from the alternator and not enough to charge the batteries. Upon further investigation I learned that I needed a sensor wire from the alternator to the primary battery. The alternator is a CS-130D and I believe it's a 105 amp model. The factory alternator plug has a 4 wire plug but only the center 2 wires are used, 1 grey and 1 orange. I bought another plug with 3 wires. The third wire was a red and would connect to the primary battery. I spliced everything in with solder and heat shrink. When I cranked up the van, everything was great. Alternator volts started out a 15.2 then as the batteries charged, finally settled in about 14.3. The battery voltage was good on both batteries and all was well. I tested it in the driveway a few days and was very happy. <;-)
I left for a couple of days and upon returning the problems started.
I went to start the van seeking more pleasure and turned the key and nothing. The idiot lights worked but the only gauge that would work was the volt meter but the check engine light came on. I checked the battery with hydrometer and digital volt meter for condition and load tested. (By the way, the van only has 250 miles on it) The battery looked good. I checked grounds with jumpers thinking I may have a loose one. I decided to jump start the van with my battery charger. Hit the key and the van started. This is where it gets wierd. All the gauges and air conditioner compressor worked for about 5 seconds. All gauges except the volt meter went to zero. I shut off the key and took it out of the ignition. The engine continued to run for about 5 seconds the stopped. During this period the check engine light was on but at a reduced illumination. I tried it again and it would not start. I tried about 45 minutes later and it would start one time and do exactly the same thing. This went on for a day or two while I was trying to figure out the problem. So to make a long long story shorter, I disconnected the isolator and exciter wire and sensor wire, the alarm system (removed the fuse and a plug to a small pink wire under the dash. I still have the same problem. I'm not sure how the GM security system works but is it possible the transponder key reader may not be working or reading the keys?
All high current wire to the batteries and from the alternator to the isolator was #4. Since I removed the fuseable link from the alternator to the battery, I installed a 125 amp fuse in line. The secondary battery has 2 80 amp fuses installed, one at either end.
Abnone have any ideas? Helm Inc does not have the service manual for this vehicle available. I'm on a list when they have it. This is extremely difficult without the factory wiring diagrams to figure out what is going on.
I hooked up my scanner and get a P1682 code which translates to low voltage on Ignition 1 circuit and lost communications with TCM. I did notice an ECM voltage in the freeze frame mode of 7.07V.
Sorry about the long winded description but I wanted to give all the facts I could.
Thanks