QuestionQUESTION: Hi Roland. You helped me with an electrical problem a few weeks ago which turned out to be fuse #8 and 16 not contacting properly and therefore the body computer was not function correctly. A new set of problems has cropped up which may again be related to the body computer. Here are the symptoms: 1) lights on the heater/AC buttons panel do not illuminate, 2)light on gear shift indicator does not illuminate, 3) when the driver door is opened normally the electronic gauges turn on, but this doe not happen now, 4) when the headlights are turned on the electronic gauges should dim, but they do not dim now, 5) the doors on the headlights seem to close much more slowly, and 6) the windshield wipers are anemic and will stop mid stroke. Help!
Thanks,
Doug Lockwood
ANSWER: Hi Doug,
Check to see the condition of fuse 18 and whether it shows full battery voltage on both sides. That one feeds the body computer and the wipers. Check fuse 14, 8 and fuse 5 similarly with the key in the run position. This may be a situation where something is shorting. drawomg down the voltage, but not blowing a fuse.
Roland
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QUESTION: Roland, when you say full voltage on both sides, am I using a volt meter, connecting the negative lead to ground, and checking both slots that the fuse plugs in to for 12 volts positive current? And for fuse 18, should the key be in the run position?
I also wonder whehter the connectors into the body computer are getting dodgy.
Doug
ANSWER: Check the voltage with one lead of the meter well grounded (to a shiny metal surface of the body structure). 14 should be hot all the time, and 5 hot when you have the lights in the park or headlight position (and you could also measure both with the key in the run position as well, just as a check). 8 and 18 are only hot in the run position of the ignition switch. The voltage while nominally 12 should actually be same as measured across the battery posts.
If the body computer might have had rain water/car wash water drip down on it then yes it would be good to pull the plugs, and spray the sockets with electrical contact cleaner. It is just in front of the right side door, at the lower corner, behind the rug trim. You have to remove the door sill, I think, to get the trim panel out of the way. Whenever water drips down from the windshield if it leaks slightly that can play havoc with the functions you listed that are related to the body computer.
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QUESTION: Hi Roland. OK, here are the results.
First I pulled each fuse and tested all four of them for continuity. They all passed.
Checked voltage across the battery terminals and it was dead on 12 volts. Don't know what the accuracy of my meter is, of course.
Attached negative of volt meter to a solid ground in the cab and probed the two sockets for each fuse with ignition off and ignition on. Here are the results:
Fuse 18: Ignition off, 0 and 0. Ignition on, 11.6 and 2.5
Fuse 14: Ignition off, 11.6 and 0. Ignition on, 11.2 and 0
Fuse 8: Ignition off, 0 and 0. Ignition on, 0 and 11.2
Fuse 5, headlights on: Ignition off, 0 and 0. Ignition on, 0 and 0
By the way, as of yesterday, we noticed that the tail lights don't come on although the brake lights work.
Thanks, let me know what the next steps are please. I do very much appreciate your help!
Doug Lockwood
AnswerHi Doug,
Fuse 18 should be 11.6 and 11.6 with the ignition on. Were the wipers on or off when did the reading? If off, then the fuse may be 'resistive' but not blown e.g a bad connection of the fuse to the socket. If on, then the wiper circuit is drawing too much current, for a reason to be determined.
Fuse 14 appears to be blown or not making good contact in its socket
Fuse 8 same as fuse 14
Fuse 5 depends upon have a good fuse 14 situation, so fix that first.
Roland
