Strange electrical issue

[petersonj]

That spec sheet looks just like the one I had when I bought my truck new, including the optional equipment which mine has. I think your truck is a Base model like mine.

I think I would start my troubleshooting with the power door locks and power windows circuit just because they are basic with relative ease for access. They both get their power from the Junction Block and both can be tested with a test light after lifting out the switches from the armrest. To remove the switch assembly, force the housing rearward against a hidden spring inside the housing and lift the front of the housing upward. The power to the door locks should be unswitched (from battery) and the power to the windows should be switched.

- John

 

[brucejohnson]

A quicky check on the door locks.
I assume the driver's door is the only one tested as not functioning. Have you attempted to cycle the passenger door lock button?
Just taking baby steps here..depending on the outcome, that may determine if the driver's door switch is bad.

AND, do you have the overhead console with compass and temperature, map/courtsey lights, etc.? Or just the hole for hiding stuff from yourself?

 

[brucejohnson]

That spec sheet looks just like the one I had when I bought my truck new, including the optional equipment which mine has. I think your truck is a Base model like mine.

I think I would start my troubleshooting with the power door locks and power windows circuit just because they are basic with relative ease for access. They both get their power from the Junction Block and both can be tested with a test light after lifting out the switches from the armrest. To remove the switch assembly, force rearward against a hidden spring on the housing and lift the front upward. The power to the door locks should be unswitched (from battery) and the power to the windows should be switched.

- John

John,
My 98.5 was an SLT which had minimal options like carpet, upgraded seating materials and a few niceties. My 2002 was an SLT+ and had almost all available goodies.
His window sticker indicates he has the SLT trim package. Were the available configurations then ST, SLT and SLT+? Could those be Base, Highline and Premium? Or was it Base, ST, SLT?
Been a while...memory cell compacted too tight with stuff.

 

[Ozymandias]

ST was the plain blank work model, SLT is second, almost nothing in it aside from a couple goodies.

 

[petersonj]

Bruce,

I think the Base, Highline, and Premium were convenience trim packages that were grouped in a certain manner which determined what they were called. I remember it being very confusing at the time. It still is. The only place I ever see Base, Highline, or Premium ever mentioned is when I am using the factory service manual. What I have noticed is that it seems that there are many more computer controlled devices in the Highline and Premium trucks.

For example, BECAUSE my truck is only a Base model even though it is an SLT, I was able to rewire my power window switches to operate without a key in the ignition switch. Not happening with the Highline and Premium models.

- John

 

[brucejohnson]

Ok, tried one more thing to try to narrow down whether this is a grounding issue or a supply issue. Dome light should be on any time a door is open, so I removed the dome light and checked for voltage, it was 0. Btw, I connected the negative lead of the multimeter to the negative battery post and then tested for voltage at each of the 2 wires not knowing which was the + or -. No voltage on either wire. Based on this, I’m guessing it’s not a grounding problem.

So both doors open will check the door switches. No power indicated.
What happens when you put the headlight switch into the dome light position? I am going to assume there will be no change.
Just for grins n stuff pull and check Fuse 12 in the Junction Block. (Not PDC) Check for power at the F12 plug in the Junction Block. Also, just for grins, do it for Junction Block Fuses 6,11 and 13. (13 would be a prominent suspect as it supplies B+ to the CTM. The other two appear to detect switch position mode).
If there are issues, I would anticipate that out of those four fuses F 12 and/or F 13 would be the ones to have an issue related to the symptoms experienced. If there is power through the fuses the CTM may have given up the ghost. This is on the assumption that you have the Highline up features. If you have a Base model, there would be way too many circuit problems to cause all the issues. As it is, we can assume a fused circuit stopping the CTM from doing its duties, or a failed CTM. The fused issue would entail other important circuits to be faulty also. Some of the associated circuits on the fuses in question would create some other evident issues, including running problems. A CTM failure may cover almost every one of your issues assuming you do not have the Base model circuitry.
Question: Do/did your doors automatically lock at a certain speed?
This may leave the power windows issue as a stand-alone event. Maybe a bad CB 1. Try swapping with CB 2.
All the others can be related to the CTM, either not being powered up or a catastrophic internal failure...or plain ol' bad juju.
There are also wiring harness and switch issues, among others. Don't want to overthink more than has already been done. Trying to maintain the KISS principle. Most of the suggested checks are quick and simple in the process of elimination.
Hmmm...Never got around to ask if there are any codes generated.
Best of luck.

 

[petersonj]

@RDMueller , does your truck have a key FOB and security? If so, your door locks are tied into the CTM. Either way, fuse 13 in the Junction Block (yes, the fuse panel inside the cab) is supplied by unswitched battery power. Does Fuse 13 have power?

You mention that you have no power to the dome lights. Do you have power at Fuse 12 in the Junction Block? Fuse 12 receives unswitched battery power and sends that power to the dome lights, map lights, cargo lights, and power mirrors.

There may be a common hot wire defect from the battery source that is affecting all of these circuits.

- John

 

[brucejohnson]

Bruce,

I think the Base, Highline, and Premium were convenience trim packages that were grouped in a certain manner which determined what they were called. I remember it being very confusing at the time. It still is. The only place I ever see Base, Highline, or Premium ever mentioned is when I am using the factory service manual. What I have noticed is that it seems that there are many more computer controlled devices in the Highline and Premium trucks.

For example, BECAUSE my truck is only a Base model even though it is an SLT, I was able to rewire my power window switches to operate without a key in the ignition switch. Not happening with the Highline and Premium models.

- John

John,
From the looks of the schematic should be able to move the CB 1 (power windows) input from the RUN/ACC to the same BATT input line as CB 2 (power seats); 50A PDC fuse to Junction Block BATT feed. Not sure if it's wires or buss bars in the backside though. Where there's a will, there's a way, as long as the magic smoke the engineers packed into the circuits isn't released. The circuits quit working once the magic smoke leaks out.

 

[petersonj]

From the looks of the schematic should be able to move the CB 1 (power windows) input from the RUN/ACC to the same BATT input line as CB 2 (power seats); 50A PDC fuse to Junction Block BATT feed

No power seat in my truck. I just jumpered the power door lock source to the power window circuit breaker. I don't use both at the same time and I have never tripped the circuit breaker in the last 22 years.

John

 

[brucejohnson]

No power seat in my truck. I just jumpered the power door lock circuit breaker to the power window circuit (after removing the power window fuse). I don't use both at the same time and I have never tripped the circuit breaker in the last 22 years.

John

That'll work, too. Electrons love the easiest way to get herded from point A to point B. But watch out, if you get enough of them together, they can bite.

 

[RDMueller]

A quicky check on the door locks.
I assume the driver's door is the only one tested as not functioning. Have you attempted to cycle the passenger door lock button?
Just taking baby steps here..depending on the outcome, that may determine if the driver's door switch is bad.

AND, do you have the overhead console with compass and temperature, map/courtsey lights, etc.? Or just the hole for hiding stuff from yourself?

Yeah, same from both sides. I’ve definitely tested all controls, nothing works. Overhead console is the basic one, no compass/temp. It does have the map lights however, and that also brings up an interesting point - the map lights work when turned on individually, but do not turn on with a door open. IIRC, when a door is open those map lights turn on along with the dome light. Sooo, those lights must have 2 sources of power and one is still working.

Also, regarding keyless entry/fob - not installed; power seats - not installed. Automatic door lock at a certain speed - not installed. I really think this is a pretty basic model, just one step up from a tradesman with carpet and cloth seats and nothing else.

Going to do some more troubleshooting today and will report back later.

 

[petersonj]

It does have the map lights however, and that also brings up an interesting point - the map lights work when turned on individually, but do not turn on with a door open. IIRC, when a door is open those map lights turn on along with the dome light. Sooo, those lights must have 2 sources of power and one is still working.

You might be on to something here. The map lights have the SAME source of power (Fuse 12 in the Junction Block), BUT they have two separate grounds. When the map light switch is activated, ground G200 is used. When map light switch is deactivated and the door is opened, a different ground path is used. This same ground path is used to turn on the dome light (also Fuse 12) when the door is opened. The door switch ground path may involve the Central Timer Module - not sure.

Fuse 12 in the Junction Block is associated with the following:

Power mirrors
Dome light
Map lights
Cargo lights
Underhood light
Glove box light
Radio

There are a lot of splices and joint connectors on the positive side and the negative side within these circuits. I think it would worth verifying which lights work and don't work using by using the various controls. Document what you find. It should make it easier to locate the problem area.

- John

 

[Ozymandias]

Interiorlights are ground switched.
Measure if you have grounds at the stuff that isn't working.

 

[RDMueller]

Interiorlights are ground switched.
Measure if you have grounds at the stuff that isn't working.

Then the dome light for example should have a hot wire at all times, in my case both wires going to the dome light are dead.

 

[RDMueller]

You might be on to something here. The map lights have the SAME source of power (Fuse 12 in the Junction Block), BUT they have two separate grounds. When the map light switch is activated, ground G200 is used. When map light switch is deactivated and the door is opened, a different ground path is used. This same ground path is used to turn on the dome light (also Fuse 12) when the door is opened. The door switch ground path may involve the Central Timer Module - not sure.

Fuse 12 in the Junction Block is associated with the following:

Power mirrors
Dome light
Map lights
Cargo lights
Underhood light
Glove box light
Radio

There are a lot of splices and joint connectors on the positive side and the negative side within these circuits. I think it would worth verifying which lights work and don't work using by using the various controls. Document what you find. It should make it easier to locate the problem area.

- John

View attachment 137797

Power mirrors - INOP
Dome light - INOP
Map lights - INOP with door open, works when switched individually
Cargo lights - INOP
Underhood light - ops normal
Glove box light - ops normal
Radio - comes on but no sound. Suspect amps built into each speaker unpowered.

 

[brucejohnson]

Power mirrors - INOP
Dome light - INOP
Map lights - INOP with door open, works when switched individually
Cargo lights - INOP
Underhood light - ops normal
Glove box light - ops normal
Radio - comes on but no sound. Suspect amps built into each speaker unpowered.

Power windows?
Door Locks? (JB Fuse 13 which also powers up the CTM)
Have you tried the passenger door switches for window and lock function?

 

[RDMueller]

Power windows?
Door Locks? (JB Fuse 13 which also powers up the CTM)
Have you tried the passenger door switches for window and lock function?

Power windows inop both sides with either control.
Door locks inop both sides with either control.
Yes, tried passenger door switches as well, all inop.
Also have checked JB fuse 13, it is good and is receiving normal voltage.

 

[petersonj]

Getting closer.

Dome light, cargo light, power mirror, radio - all get their power through Joint Connector #5 which is downstream of Fuse 12.

Dome light, cargo light, and power mirror get their power from Pin #13 of Joint Connector #5. The power continues through Connector 203, then Splice 310.

Start with the upper diagram and follow Connector 203 with the letter "A" inside the triangle. Pick up the same connector in the lower diagram.

I think part of your problem exists either in the wiring or connections including Joint Connector #5 through C203 and arriving at S310. Note that the power for the underhood light and glove box light (which are both working) come from the Junction Block and Joint Connector #5 respectively. They both have separate grounds as well.

- John

 

[brucejohnson]

Power mirrors - INOP - Fuse 13 - Also Feeds CTM B+ (12vdc)
Dome light - INOP - Possible routing through CTM - Still researching
Map lights - INOP with door open, works when switched individually - Individual switching via direct ground circuit. Possible routing through CTM - Still researching
Cargo lights - INOP - JB Fuse 12 - G300 - Dome, Cargo, Glove Box, Under Hood, Overhead Console, Power Mirror, Radio, Data Link Connector.

Dome and Cargo Possible routing through CTM - Still researching​

Underhood light - ops normal
Glove box light - ops normal
Radio - comes on but no sound. Suspect amps built into each speaker unpowered. - Possible routing through CTM - Still researching.

Joint connector 8 has been challenging as a couple schematics directed to another, and wasn't found. Probably from an older set and overlooked in the reroute change.

Definitely challenging...

Thanks John for the digital schematics. I have the big bulky book with rice-paper-like pages...full of bookmarks to bounce around in.

Thanks RDMueller for the additional information. This helps a lot.

 

[RDMueller]

SOLVED!!!

Will be back in a few minutes with pictures