bad alternator??

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semlin

curmudgeon
Joined
Mar 27, 2003
Messages
5,237
Location
north of 49
sure sounds like it, but just in case I'll see what mud thinks.

the bad alternator light came on suddenly today, along with the at overheat and oil lights. I stopped the truck and afterwards it turned over strongly but would not start. changed the efi relay for the spare and it made no difference. a while later it started but idled very poorly at about 450 rpm with the trouble lights off, but ran apparently normally. I limped it home where the lights came on again and it died across the street :rolleyes:

I have checked all the connections and can find nothing bad. there is a small rad hose weep from the top rad hose close enough to the alternator for it to have sprayed there.
 
ok this is weird. the tranny shift lock is engaged so that I cannot take it out of park even with the brake pedal depressed and the ignition switched on. the only time that happened before was a problem with the trailer harness.

I was towing with the truck just before this happened and had just disconnected the trailer. maybe i had better remove the harness.

i have double checked and all fuses appear to be fine.
 
ok, perhaps it is a ground issue??

it seems I have no brake lights or tail lights and only one headlight, and the heater fan is permanently stuck on at a low level and does not respond to the fan control.

I have inspected all ground connections and they seem fine. I am going to clean and redo the body grounds but this is weird.
 
fusible links were fine, but I had to disconnect the positive battery terminal to check them. that solved the problem at least temporarily so I could drive home. when i reconnected the battery the old "disconnected" alarm armed. I think it is not as disconnected as the alarm store claimed. I looked under there and the brain is still in place :mad:
 
You have not stated what your voltage is (as Atoyot1031 asked). Closer to 12 than 14, and/or no change with vehicle on/off (key "on") points to alternator, or at least a bad battery connection.

Curtis

my voltage meter is missing a probe so i cannot tell you the answer. as noted, though, somehow I have activated and armed an old alarm. after disconnecting the positive battery terminal to check the fusible links and then reconnecting it, the engine suddenly fired and the other noted issues with lights and fans were rectified. but when I did this the old alarm light also lit up and the arming sound came on. i drove it across the street home where it promptly stalled.

it might have been a bad connection, although the fact the starter cranked suggests otherwise, or it may be the alarm. I will remove the alarm tomorrow. tonight I was just glad to get it home.
 
ok, update:

Does anyone have a 93 EWD and is willing to try to help me isolate some symptoms? My next step is to start taking the fusible link wiring loom off backwards from the battery and check for brakes. I was hoping to isolate it to a particular link and section of the loom based on the symptoms below.

I completely removed the alarm a while ago. I am confident there are no faults caused by the alarm wiring anymore. I have also cut out my trailer wiring harness and checked that there are no bare wires on the truck wiring. I was towing just before this started, and had just disconnected the harness (with the truck turned off), but that might be a coincidence.

since cutting out the alarm, the problem has come back, but not nearly as often and I have not had the harsher symptoms again (yet).

The engine has to get warm and I have to drive for a while for the problem to happen. I can fix the problem for a while by disconnecting the fusible links from the positive battery terminal.

after reading these two threads:

https://forum.ih8mud.com/80-series-tech/193157-real-time-help-2.html

https://forum.ih8mud.com/80-series-tech/142213-real-time-help-fuel-delivery-issue.html

I think I have a wiring harness issue on the positive side or possibly a bad brain like grench did. I am wondering if anyone has the 1993 EWD and might be able to suggest where the fault would be to get these symptoms..

when it occurs, I have had (at various times) the following symptoms:

1. the alternator gauge red light comes on

2. the alternator gauge goes dead and centres

3. i get 3 dash trouble lights, AT, Oil and brake

4. no brake lights or tail lights

5. The dash heater fan gets permanently stuck "on" at a low level and does not respond to the fan control.

6. tranny shift lock engages even with the truck off and my foot on the brake

7. engine stalls

8. engine will turn over but not fire

9. engine may restart on its own after leaving it for a while, but when engine restarts idle revs are very low behaves as if the battery has been disconnected

10. engine will restart if you disconnect fusible links at the battery, wait and then reconnect.

symptoms 1-3 are more common and go together. They are completely intermittent and random and can last 5 seconds or 30 or stay on until you kill the motor. When they cease the alternator immediately shows it is fully charging.

I only had the other symptoms before I cut the alarm out. They might have been caused by the alarm or, as I now suspect, this problem simply went underground for a while??

all the connections at the alternator look fine. It had new brushes 20k ago. I can see no signs of contamination of the alternator and I have not gotten it wet lately. the battery and fusible link connections are also good. All of the fuses in the truck appear fine and I have swapped relays out.

I am also seeing the oil light alone coming on at random for short periods which may be unrelated. I have lots of oil and good oil pressure. The truck has always done this on a very very intermittent basis but now it is daily.
 
I'm leaning toward where I pointed you.
 
Send a PM to TrickyT and point him to this thread. He has an amazing grasp of the EWD as it relates to the engine and charging circuits.

-B-
 
Send a PM to TrickyT and point him to this thread. He has an amazing grasp of the EWD as it relates to the engine and charging circuits.

-B-

That is a classic example of understatement.


The guy is brilliant......:beer:
 
Sheesh, talk about pressure to perform. ;)

I do think the basic problem here is a bad electrical connection, either on the +12v side or possibly at one of the major ground points, but it's hard to say where without studying the EWD. One potential problem in trying to figure this out is that I've only got a '97 EWD but Simon's rig is a '93 and I'm not sure what the differences are. I'll have a look at my EWD when I get home tonight.

Simon, just to clarify: have you actually swapped out the the fusible links or have you just inspected/tested them? These are cheap, $10-$12 IRRC, and hence would be worthwhile to replace if you haven't done so already. Even if your old links are not the problem you can always keep them as a trail spare. Secondly, find a probe for your multimeter. This is almost surely going to come down to testing electrical circuits and you're going to need a functional multimeter for that.

More later.
 
thanks Tom,

i agree that the difference in years may be an issue but at least you have an EWD, and I do doubt that toyota messed with the engine bay wiring configuration much.

I have checked all the grounds in the engine bay and I have removed and cleaned the firewall ground. they all appear to be good.
 
Well this is definitely a weird one. Many but not all of the symptoms indicate a power supply-side problem. The lit alternator light and centering of the voltage gauge is a clear indication that the alternator is not producing any power. The inoperable stop lights, tail lights, tanny shift lock, inability to start, and rough running after starting all indicate to me that many of the circuits getting power from the "main" fusible link are dead or go dead intermittently. Charging of the battery also goes through this link. But so do the headlights, and you've never made mention of any problem with the headlights. So one key question: have any of your problems ever happened at night when the headlights were on and if so what symptom did they exhibit? If the headlights go out too, then it's definitely an indication of a problem with the main fusible link and/or the wiring from this link. If the headlights are unaffected, then I would carefully inspect the main power lug on the alternator, the one covered by the rubber boot. This was the source of the problem with Rory's truck (see https://forum.ih8mud.com/80-series-tech/193157-real-time-help-2.html for details). You may have to carefully strip back the insulation from this lug in order to inspect it. Any signs of discoloration of the wires or overheating of the insulation would be cause for suspicion.

The heater fan sticking on is a symptom in conflict with the ones above (from the perspective of the EWD), and I have a few questions about this. When the fan comes on, does the "low" LED indicator also come on, or is it just the fan motor without any LED indicators? Has the fan coming on occurred in combination with any of the other symptoms you list in post #10 and if so which one(s)? And when you say that the fan "does not respond to the fan control" do you mean that if you push the "hi" switch the fan won't speed up? The heater fan can only come on if the heater relay gets energized and there are only limited ways for this to happen. I'm still trying to figure out how this is tied in to the other symptoms above.

Lastly, the issue of symptom #3 - the three dash trouble lights: A/T over temperature, low oil level, and brake fluid level/parking brake. From your earlier posts it sounded like these could come on when you were just driving down the road. Is this true? Specifically I'm asking if these lights ever come on together when the transmission is in "D". A bulb check relay has to get energized for these lights to come on together and there's no power source to this relay when the tranny is in drive.

Ok, that's what I've got so far. More questions really than anything specific, but your answers will help eliminate possibilities. Oh yeah, it is most definitely NOT the ECU.
 
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tom that is awesome. it makes more sense than you think

extra detail triggered by your comments:

1. i did initially think i had a headlight problem on one side. but since the problem remained even with everything else ok, i think it is a bad bulb. that side burns out bulbs very regularly.

2. the headlight switch on my truck is live with the ignition off

3. when the headlight switch is "on", even with the ignition off, the heater fan also works

4. when my truck was first imported into canada daytime running lights were retrofitted at the first and last garage i have taken the truck to. didn't think about it, but obviously they jumped some wires somewhere, and that jump may be connected to the symptoms above.

5. the daytime running lights are less bright than when i turn the lights on to low beam.
 
i am thinking i need to look for a DRL wire splice into my main fusible link connector to the alternator
 
ok the drl was accomplished by jumping directly from a wire (cut) going into the headlight relay in the engine bay fuse box to a black wire with an orange stripe (cut) that went into one of the two steering column plugs. I have cut out the jumper and reconnected at both ends to the original wires so hopefully that will eliminate some of the funny business. hopefully i don't get a ticket for having no DRLs.
 
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and by funny business i hopefully mean these ones below. yes the heater fan would be on at a low level but the heater fan control buttons would not work, and yes the dash lights i mentioned would come on while i was driving in D. hopefully the mysterious black with orange wire somehow energized these puppies, but I am looking around some more under the dash for shenanigans.

The heater fan sticking on is a symptom in conflict with the ones above (from the perspective of the EWD), and I have a few questions about this. When the fan comes on, does the "low" LED indicator also come on, or is it just the fan motor without any LED indicators? Has the fan coming on occurred in combination with any of the other symptoms you list in post #10 and if so which one(s)? And when you say that the fan "does not respond to the fan control" do you mean that if you push the "hi" switch the fan won't speed up? The heater fan can only come on if the heater relay gets energized and there are only limited ways for this to happen. I'm still trying to figure out how this is tied in to the other symptoms above.

Lastly, the issue of symptom #3 - the three dash trouble lights: A/T over temperature, low oil level, and brake fluid level/parking brake. From your earlier posts it sounded like these could come on when you were just driving down the road. Is this true? Specifically I'm asking if these lights ever come on together when the transmission is in "D". A bulb check relay has to get energized for these lights to come on together and there's no power source to this relay when the tranny is in drive.
 

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