I don’t think I mentioned that I replaced the truck’s two batteries a couple of months ago. The truck was not starting reliably and both batteries were over 10 years old. They didn’t owe me anything.
But the replacement batteries had less power than the old ones – 650 cold cranking amps rather than 850. I figured that the lower power rating would not be significant for a truck is never in cold weather and is rarely used. After I installed the new batteries I found that the cranking was somewhat more sluggish, but the truck started right up. Good enough.
But 2 days later it once again would not start. Wouldn’t even turn over. Worse, when I turned the ignition the dashboard went completely dark – total electrical failure. But I was able to get it started with a jump from the Toyota. I bought a new jumper cable and a trickle charger and was confident that if I left the truck on the charger it would start reliably.
Nope. Wouldn’t start again after being on the trickle charger, despite the device that monitors the health of the truck reporting that the batteries were fully charged. Hmmm… time for some investigation.
So after a month of trial-and-error I have pretty much figured it out. It appears that there are 3 problems:
- The starter relay. This part, located in the fuse box, is responsible for taking a low-voltage signal from the ignition switch and activating the high-voltage circuit to the starter. This part seemed to be working intermittently. When I switched it with an identical part on a different circuit the starting behavior became much more predictable. I got a new part (about $15) and fixed this particular problem.
- The ignition switch. It seems that it sometimes works and sometimes doesn’t. But I have found that if I turn the switch and nothing happens, I just try again and it works. This should be fixed eventually but it is a relatively minor part of the problem.
- The leaky circuit. Even after identifying the other two problems it was obvious that something was draining the batteries when the truck was sitting idle. So I started pulling fuses and watching for a change in the rate the battery drained. I started with the few 30A fuses, then the 20A fuses. No change. There were a lot of 15A circuits so I pulled 5 of them. No change. Then another 5 (replacing the fuses after finding no change, of course). Still draining. Then another 5. Hmmm… no drain. So, one by one, I tested those 5 circuits. I finally identified the problem: the ECMRPV circuit. I don’t know exactly what that is, but it is one of the two ECM (electronic control module) circuits. The “brains” of the truck. So it appears that some brain surgery will be required. I doubt that I can do it myself, so another trip to the shop will probably be needed.
Frankly, I am not totally sure that the last two problems are not the same problem – the ECM. But I will need to fix the ECM problem and then see if there is still an ignition switch problem
*sigh* I am putting a lot of money into a vehicle that I rarely use. But as long as I have the RV I need the truck.