Trailblazer/Envoy Cold Start Issues

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4,479
Location
Kuwait
Waiting on a new amp meter to arrive before I diagnose, but thought I'd ask for some opinions in the meantime. '05 Envoy 4.2L L6 (134,000 miles); couple of days ago, after the truck sat for five days, the engine cranked very slowly and would not immediately start. The headlights and reverse lights, which turn on when the doors are unlocked, were bright as usual. Generally, once you click the ignition switch to the start position, it auto starts. But the allocated second or two for auto start wasn't long enough to fire up the engine. It needed a second attempt, holding the ignition switch in the start position for roughly 4 seconds before the engine finally fired up. The engine cranked over much slower than usual. I did not pay much attention to whether or not the headlights dimmed excessively, but the backlighting on the gauges dimmed considerably. Since the dome lights are LEDs, they didn't change much. For some reason, however, my fog lamps turned on once the engine started. My first thought was battery; a Motorcraft BXT-78-E (800 CCA) sourced from East Penn Manufacturing and installed on October 14, 2017 with roughly 18,250 miles on it. Average battery life around here is 12-18 months, although I still have 8 months left on the warranty (36 months). Grabbed my battery booster, and once I arrived at my destination, the truck sat for a little over 90 minutes. Before using the booster, I was curious to see if it would start - it fired right up with auto start! It cranked strong and took less than 2 seconds before the engine was running. When I got home, I hooked it up to my OptiMate battery charger with the battery in the truck. It did not go into "Save" mode (severely low voltage/sulfated battery) after doing a self test of the battery, and proceeded to "Charging" mode. About an hour and a half later, the battery was fully charged and optimized, and it passed the test - the charger stops charging for a specific period of time, monitoring voltage, before testing the battery again. Decided I would drive the truck daily for the next couple of days. The following morning, it cranked over slower than usual but started. The truck then sat for a little over 9 hours at work, firing right up with zero issues. I did not hook it up to the battery charger this time but measured battery voltage when I parked - 12.7V. I checked battery voltage again after 4 hours - 12.5V. After the truck sat overnight for 14 hours, ambient temperature was 54°F and battery voltage was now 12.22V. All lights were on nice and bright. It cranked over very slowly, and refused to start on 3 attempts with backlighting on the cluster dimming considerably. Since this is a side post battery, with nowhere to secure the multimeter leads and no assistant, I couldn't measure cranking voltage. I hooked up the booster, and let it sit for a minute. Although it turned over a little faster, albeit still slow, the engine started. Got to work, the truck sat for 9 hours and fired right up again with no issues. Although I was supposed to measure resting voltage, I forgot. Parked the truck when I got home, measured battery voltage and it was 12.65V. Checked again after 4 hours, voltage was now 12.5V. The truck sat overnight again for 14 and a half hours. This morning, battery voltage was 12.26V and ambient temperature was 57°F. The engine turned over real slow, and auto start disengaged. Holding the ignition switch in the start position for a couple seconds and noticed cranking got slower and slower. Pulled the booster out, and hooked it up. After a minute, it turned over slow but started. The foglights came on by themselves again, and now I noticed the headlights were out. Turned auto lamps off and turned them back on again, but the headlights wouldn't turn on. Manually flipped the light switch to the on position, and the headlights turned on. Turned off the lights completely and set them back to auto lamp mode, now the headlights were on. Now I'm going to see what resting voltage is after it sits for 9 hours, but I'm wondering the possibility of high amperage draw by the starter causing havoc with other modules on the truck. Will be interesting to see what the amp readings will be once my new one arrives. Going to check all connections, grounds, etc. in the meantime.
 
Messages
13,100
Location
ROCHESTER, NY
While the engine is running, check the alternator output. Just connect your meter to your battery +/-. It should read >14V(I believe). Others will chime in with more/better info. This should tell you that the alt is OK & doing its job. Personally, I think your battery is on its way out. I just went through this whole process(just what you're doing) with my SILs '14 GMC Terrain. It was acting the exact same way your Trblaz/Envoy is.
 
Last edited:

Falcon_LS

Thread starter
Messages
4,479
Location
Kuwait
Originally Posted by Char Baby
While the engine is running, check the alternator output. Just connect your meter to your battery +/-. It should read >14V(I believe). Others will chime in with more/better info. This should tell you that the alt is OK & doing its job. Personally, I think your battery is on its way out. I just went through this whole process(just what you're doing) with my SILs '14 GMC Terrain. It was acting the exact same way your Trblaz/Envoy is.
Forgot to mention, alternator output varies between 13.9V - 14.4V. Hopefully it is the battery, just to keep it simple and not have to be messing with anything else!
Originally Posted by chemman
Have you load tested the battery to make sure it does not have a bad cell?
Got a fancy battery tester in the mail just for that purpose. thumbsup
 
Messages
499
Location
South Carolina
My 2007 TB had some weird intermittent issues like ABS light coming on, A/C not working, and having to restart after first crank. Only thing common to all is the ignition switch. In the old days when you turned a switch, you forced contacts together. These new switches engage by spring pressure. When you turn the switch, cams move away and allow the contacts to close. As the contacts age they oxidize much like the old ignition points and create a voltage drop. Some computer modules don't boot up properly with low voltage. Short story, I replaced the ignition switch and have had zero issues since.
 

Falcon_LS

Thread starter
Messages
4,479
Location
Kuwait
An update to this post. Checked for parasitic draw, and in sleep state, after the truck was sitting for 3 hours with the hood open, it was drawing 38 mA. Since the battery tester arrived with the new amp meter, I also checked the battery. It's time to get the receipt out and replace it.

PSX_20200211_090647.jpg
 
Messages
703
Location
UK
Internal resistance meters i find work well and fast to do quick battery tests. Well worth the investment.
 
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