1996 2500 2 dr Electric Door Lock

[ginger743]

Hi Everyone,

With the weather much warmer these days I thought I would go after fixing some electrical problems on the Truck.

1) Approx a year ago the power Door Locks stopped working
2) Approx 6 months ago the daytime running lights stopped working.
3) Approx 2 weeks ago all of the interior courtesy lights stopped working.

I thought I would go after the Door Lock problem first since it's handy to have them for unlocking the doors with a " key bob " , or whatever it's called :>) . I have isolated the Circuit City installed Python burglar alarm out of the equation, the door locks should work manually with the operation of the switches on the doors , ( they used to ) :>)

Well, I have all of the Helm service manuals for this truck and have spent hours studying the door lock circuits. First of all the right door will unlock with the switch on it's door but that's all that works for the door locks , the right door will not lock with the right door switch. I figure there is either a switch problem in the right door or a bad , " motor " in that door, I'll get back to that after I get the left door operating.

Multiple problems are always fun :>)

In the manual the circuit picks up 12 volts at the I/P Fuse block, the fuse is good , then it goes from there to the Convenience Center , ( Orange wire all the way to the door lock switches according to the Helm service manual schematic ) . In the left door there is a factory splice which takes 12Volts to the passenger Door Switch in the " Crossbody Harness " still an orange wire .

The Orange wire is supposed to go on to the left door switch. Here is the problem . There is power at the right door switch, ( orange wire ) . There are 5 wires on the left door switch and none of them are orange and none of them have 12 volts on them .

My goal here is to get the 12 Volts to the left door switch. I'm writing here in case someone has run into this problem before , ( the wire changing color ) . I'm wracking my brain trying to come up with an approach to tracking this down short of unbundling " untaping " the wire bundles.

The only fuse in the circuit is in the I/P Fuse Block and it's ok. the circuit just goes in and out of the Convenience Center thru 2 connectors, one in and one out , no fuse

Any ideas on tracking this down would be greatly appreciated. I need to find out where the orange wire changes color :>) The Helm Schematic shows this 12 Volt Circuit wiring Orange all the way from the I/P Fuse Block , ( 12 Volt source , hot at all times ) to both Door Lock Switches on the Doors.

Jerry

[DennisG01]

It kinda sounds like you just have a bad switch or two. Try taking the switch out and cleaning it - it could just have dirty contacts. I've used Brakleen for this in the past with good results. Or, you may just need to get a new switch.

[ginger743]

It kinda sounds like you just have a bad switch or two. Try taking the switch out and cleaning it - it could just have dirty contacts. I've used Brakleen for this in the past with good results. Or, you may just need to get a new switch.

Hi Dennis,

Thanks for the reply ! Last year in my first attempt to repair this I used the, " shot gun method " , I replaced the switch and that didn't fix it. The dealer was gracious enough to allow me to return the new switch.

The ' actuator " is referred to as a , " motor " in the Helms Manual. What it is , is a Bi-directional solenoid . When the switch is pushed in one direction, say, " open" it applies +12 Volts to one terminal on the . " Motor " and it pulls the door linkage to unlock the door. Then to lock the door the switch is pushed in the other direction , " it's a " rocker switch " and this reverses the applied polarity causing the , " motor " to go to the other end of it's " travel " to unlock the door.

Nothing can happen until I have the 12 Volts on the switch to operate the , " Motor " in either direction.

The Manual tells me where the splices are in the harness as measured in cm from the various breakouts in the main harness .

My next step is to " tear into " my instrument panel to document how the Python Alarm system is tied into the door lock circuit, I haven't done that so the Alarm system is really not out of the picture as being the problem. How the Alarm is tied into the vehicle is a big secret and I don't have access to that information unless I'm a registered dealer / installer and I have to have the shop I work for do that registering for me, and of course Circuit City is no longer or I could have them trouble shoot it.

What makes this so difficult is that it's so hard to get to the various wires for check points. I have to take the Instrument Panel apart to access the Alarm System and most of it's wiring to document how it interfaces with the electrical/door lock system. I do want to check that out first, then I'll check out that " splice " where the 12 volts to the right door is picked up. Since the right door has 12 Volts that tells me that the circuit is good all the way back thru the convenience center and fuse block, including the fuse . I'm just losing the 12 Volts from the right door splice to the left door switch.

I'm going to work on this until I fix it this time :>)

If you have anymore ideas let me know. I'll be sure to post what the problem was after I find it :>)

Jerry

[DennisG01]

That's strange - darn near almost all of the time (at least from my experience and what I've read) the problem is in the switch.

When you tried replacing the switch... was it the passenger side of driver's side? I "think" that I remember reading that the passenger side switch goes through the driver's side (sort of like the driver's side being the "master"). Meaning, if there's a problem on the driver's side, the passenger side may also act funky, even though it may be fine.

Just thinking out loud here... Could you try jumping 12v to the switch to see if you can get the "motor" to work? That would at least eliminate some of the variables. My suspicion, though, is the passenger side motor is fine - since it does work, although only in one direction.

I have a subscription to AllDataDIY - I can check that to see if there's a better diagram.

[DmaxMaverick]

The term "motor" may be more correct than it seems. Only on OTR trucks have I seen actual "solenoids" used for door unlocks. Every automotive type has actually been a motor, like a screw-jack, or stepper type actuator. They do seize, from time to time. Applying power to the extend and retract poles should easily determine if that's the case.

[ginger743]

That's strange - darn near almost all of the time (at least from my experience and what I've read) the problem is in the switch.

When you tried replacing the switch... was it the passenger side of driver's side? I "think" that I remember reading that the passenger side switch goes through the driver's side (sort of like the driver's side being the "master"). Meaning, if there's a problem on the driver's side, the passenger side may also act funky, even though it may be fine.

Just thinking out loud here... Could you try jumping 12v to the switch to see if you can get the "motor" to work? That would at least eliminate some of the variables. My suspicion, though, is the passenger side motor is fine - since it does work, although only in one direction.

I have a subscription to AllDataDIY - I can check that to see if there's a better diagram.

Hi Dennis,

I just typed a long reply and explorer dumped on me, I didn't have this problem with IE8.

Yes one would think that the weakest link in the system would be the switch, that's why replacing it was the first thing I did last year. Highest probability of failure :>)

Wiring or splices would be the last place to look other than the vehicle having been in a collision or some mechanical , " disruption " . That's why I want to take a good look at how the Circuit City Alarm Installation interfaces with the vehicle door lock wiring next.

I have the schematic of the system in the Helms Manual and yes the two doors do work together but the left door does operate independent of the right door. In the right door it has either a bad switch, Motor or wiring , that covers the entire system for the right door to operate independent of the left door. :>). The right door should be an easy fix other than the mechanical part of getting to and replacing the bad part(s).

It's also kinda strange to have multiple problems that so far appear to be unrelated !!

Anyway I think this is good exercise for the Brain to keep it operating as long as we can :>)

I'll be working on this after lunch and I'll keep you posted on what I find.

Jerry

Doing an edit here to add another comment

I forgot to add. I did consider Jumpering in 12 Volts to the left door switch , I may do that as a quick test/verification of the problem in that door. Since it doesn't have the orange wire it should have I would have to verify which terminal to place the 12 volts on.

I replaced the drivers side switch .

Great idea checking " alldatadiy " , could you check on what the colors are for the 12 Volts to the right and left door switches, Helms calls for orange and it's on the orange wire on the right door but the left door doesn't have an orange wire.

The more I " kick this around with you " the more suspicious I am of that Alarm Installation !

[DennisG01]

Great idea checking " alldatadiy " , could you check on what the colors are for the 12 Volts to the right and left door switches, Helms calls for orange and it's on the orange wire on the right door but the left door doesn't have an orange wire.

Sure, I'll check on that. In the meantime, is one of the wires on the driver's door bigger than the others? If so, I would think that would be the feed/12v wire.


EDIT:
And, yes, I would NEVER "count out" some kid installing an aftermarket alarm as a possible problem. I had a remote start installed a number of years ago. Shortly after I started having a "no-start" scenario. They said NO WAY it could be something they did so I ended up replacing the ignition module. Everything was fine, for a bit. Started happening again and I kept thinking it was something with the remote start. I took it to a VERY reputable installation place and they found shoddy workmanship of the wire splices for the remote start. Disabled the remote start and everything has been fine - it's been almost 3 years now.

Your remote start is probably (although you likely already know this) just tucked up under the dash (below the steering wheel). Maybe just follow some of the wires and see what the splices look like?

[ginger743]

Sure, I'll check on that. In the meantime, is one of the wires on the driver's door bigger than the others? If so, I would think that would be the feed/12v wire.

Hi Dennis,

There are 5 wires to the switches and they are all the same size.

I'm going to write down the wire colors for both doors and compare them to each other and the schematic.

I made a number of edits to my last post, you might go back and check it. they were mostly comments to your previous post that I forgot to put in that original post.

[ginger743]

Sure, I'll check on that. In the meantime, is one of the wires on the driver's door bigger than the others? If so, I would think that would be the feed/12v wire.


EDIT:
And, yes, I would NEVER "count out" some kid installing an aftermarket alarm as a possible problem. I had a remote start installed a number of years ago. Shortly after I started having a "no-start" scenario. They said NO WAY it could be something they did so I ended up replacing the ignition module. Everything was fine, for a bit. Started happening again and I kept thinking it was something with the remote start. I took it to a VERY reputable installation place and they found shoddy workmanship of the wire splices for the remote start. Disabled the remote start and everything has been fine - it's been almost 3 years now.

Your remote start is probably (although you likely already know this) just tucked up under the dash (below the steering wheel). Maybe just follow some of the wires and see what the splices look like?

Hi Dennis,

I left the truck at Circuit City for the install , I then went to Starbucks nearby to kill time , didn't take too long for them to install it. I have a relatively basic system, no remote start.

First thing I'll do is pull the " dash " to get at the alarm and most of the wires I can't get at any other way and check it all out and document how it's all wired into the truck. I already replaced the relay module for the alarm door lock system.

Gonna be a fun afternoon.

Later, Jerry

[DennisG01]

This is for my '98, so maybe it's different for yours? Don't why it would be, but who knows.

Looks like it's supposed to orange on both sides. But it also looks like the final feed to the motors comes from the passenger side?

[ginger743]

This is for my '98, so maybe it's different for yours? Don't why it would be, but who knows.

Looks like it's supposed to orange on both sides. But it also looks like the final feed to the motors comes from the passenger side?

Hi Dennis,

Fantastic !!!! I sure appreciate your help here !!!

Your schematic looks identical to mine .

Look at the switches represented by the 2 " boxes " , at the top center of the boxes at " D " is where the 12 Volts come into both switches from the Convenience Center in the center of the 2 Boxes and above them . I agree, stepper Motor is a better description !

There's a connector , " C 209 " just before the 12 Volts gets to the switch, another good place I can check, make sure that connector is connected ok and if I have 12 Volts there. I can also verify the wire colors in and out of that connector.

The left door " lock function " does go thru the right door switch !! I still need 12 Volts at the left door for other function though.

Jerry

[ginger743]

Well .....

I was going to compare the door lock switch wiring, right and left, they are different and I didn't want to take the time to figure them out and compare them. I then refocused on looking for the 12 volts to the left door switch and tracing out how the alarm system interfaces with the truck wiring.

I removed the Instrument Cluster Bezel and the Knee Bolster panel under the bezel. That didn't buy me much. I did see the alarm module squeezed in behind the light switch with splices to the switch wiring and 2 fuses which were good. The blinking parking light feature when the alarm is put in alarm mode and taken out of alarm mode work just fine so I moved on to looking for the door lock relay interfacing and the missing 12 Volts.

I found the alarm door lock relay " box " behind the left kick panel and it's wiring goes thru the rubber " conduit " that carries the wiring harness from the door pillar into the door. I had replaced this relay " module " last week and wired it with a plug rather than having it hard wired. That didn't buy me anything but at least it's mounted with a plug and easily removed for replacement etc.

I found that the splices for that relay , " module " are in the rubber Conduit that goes from the door pillar to the door. I can't pull enough of the harness out of the door to get a good look at the splices, they are taped with black electrical tape, seems they would have used heat shrink tubing over the splices . I was able to look at one splice and at least it was soldered.

I found the connector I previously mentioned and the wire size doesn't match the wire size at the door switch. to make a long story short I'm going to get an early start in the morning and remove the door mounting panel assembly so I can do the tracing I need to do.

Until I have a diagram of how the Alarm Door Lock Relays are wired into the Door Lock circuit I'm not looking at the entire circuit. I also need to find that 12 Volts for the switch.

They certainly installed the Alarm System in such a way to make it most difficult to tamper with or defeat , and work on :>)

When I started trouble shooting I found the 12 Volts missing on the left door so I concentrated on finding that rather than work on the entire operation of the system. I figure that the 12 Volts is needed no matter what and thought it would be easy to find. So much for that thinking.

I'm trying to stay focused here and work the most obvious problem rather than jumping around , for example working on the right door switches. I'll take a look at them after I get the 12 Volts. Actually the right won't work without the left and the left won't work without the right switches. After I get the 12 Volts I'll verify that the left door switches are good, have continuity thru them that the right door needs. The right door switches get their grounds thru the left door switches.

Dennis I reread your post and you are exactly right;

"Looks like it's supposed to orange on both sides. But it also looks like the final feed to the motors comes from the passenger side? "

I was too focused on that 12 Volts :>)


Anyway, that's about it . I hope to fix this mess tomorrow. I'll keep everyone that's following this , updated :>)

Are we having fun yet ? :>)

Jerry

[DennisG01]

Well, I think I'm having more fun than you since I'm not currently contorting myself into all sorts of weird looking positions under the dash!

You mentioned that it looks as though the connections that were found in the rubber boot are soldered. This may be a long shot, but having a soldered connection is not always a good thing. If the "solderee" doesn't know what he's doing, he will apply too much solder and actually weaken the joint. What happens is the solder is allowed to flow too far into the strand and creates a very acute flex point, not allowing the wire to bend naturally in an arc.

Considering where this joint is located and the constant flexing it is under each time the door is opened/closed (not to mention vibration going down the road), that could be a likely culprit.

[ginger743]

Scroll down, I did a big update to this post .



Hi Dennis,

Taking a break here, it's cold out there but is warming up quickly. I'm doing this work in the driveway :>)

I understand about the solder " wicking " and stiffening up the wire. In " the old days " I built a lot of HeathKit Ham Radio gear and got pretty good with the soldering. In this case not enough solder was used and it didn't flow well, kinda looked like bird droppings on the wire, not enough heat . The splices may have been working ok bit I trimmed them, tinned the wires and used crimped and soldered butt splices covered with heat shrink tubing.

Yes ! I don't like where they accessed the harness at that flex point where there is flexing when the door is opened and closed, I'm going to be sure there is plenty of freedom in the harness at that point so it can kinda move in and out of the door as the door is opened and closed, that would be the ideal.

The way the circuit works is that since the Transistors in the main unit can't handle enough current to drive the door motors , what they do is take the open closed signals out of the main unit and drive the relays that are interfaced with the OEM Circuit driving the Motors.

The "cross body" leads are cut at the " White " and "Light Blue " , ( on the schematic ) wires and the Alarm Relay contacts are put in series with these White and Blue leads supplying open and close " signals " polarities just like a door switch would. With the Alarm Relays in the de-energized position they just pass the door switch signals thru like the Alarm Relays aren't in the circuit.

On the Schematic the " P " designations are Grommets . They " broke into " the circuit at the P500 Grommet , it's the one where the harness goes from the door pillar into the door , at that boot looking rubber that is seen when the door is open. On the Schematic it's just under the left door switch.

Yup, it's no fun sitting on an old milk carton type of box working in the door hinge area . When I do stuff that is tedious or isn't much fun I tell myself. " I just have to do this one time " :>)

Well, back to it. On to " hunting down " the 12 Volts :>)

Later , Jerry

Okaaaaaaay ,

A little update here. I'll just add onto the previous post with this edit .

I finished up redoing the splices in the pillar to door " boot".

I then went looking for the 12 Volts. I started from scratch because things weren't making sense, wire changing color and size . I re-verified that I was looking at the correct Connector, ( Helm Service Manuals are great ). I went to the connector section in the Manual, it gives the drawing of the connector along with the wire colors and , " pin-out " along with a description as to what appears on each wire. I had been looking at a connector that had 5 wires on it , " assuming " that it was the 5 wires I was looking for , for the door switch , WRONG !!!That assume thing ya know ?

I checked the voltage on the Orange wire I was looking for on the correct connector and it had 12 Volts on it as Helm indicated . I plugged in the lock switch, hooked the batteries back up , ( I had disconnected the batteries after finding the 12 Volts so I could hook up the lock switch with power off ) and what do you know, I can lock and unlock the right door, I can't do the left door because it's motor is on the panel that I removed to get at the splices in the harness. I'll recheck it again, checking the left door after I install the panel and before I totally button it up.

Those splices didn't look absolutely bad but didn't look that great either, oxidized wires twisted together with solder sitting on top of them. Along with black electrical taped splices with the tape coming off . I think there will be enough extra wire , ( amazing, GM usually measures wires to the inch, absolutely no extra ) :>) to push the spliced area of the wires into the pillar and away from the " flexing " area, I'll see after I re-install the panel.

Now all I have to do is put it all back together. It's a shame I had to open up the door but I had to , to get at those splices unfortunately.

That's it !! Just grunt work to put it back together .

Jerry

[DennisG01]

That's great, Jerry! What do you think the actual problem was?

I don't know why I didn't think of this before, and it's probably a moot point now, but here is a picture of the door lock connector on my driver's side. It does, indeed, show an orange wire and it is hot with 12v. I know yours isn't orange, but I would assume the positioning should be the same.

[ginger743]

Hi Dennis,

Yes !! The 12 Volts was on an Orange wire when looking at the correct connector !! I guess we could trace out the problem with the symptoms I had, Drivers side totally inoperative and passenger side unlock only. I think more than one of those splices had failed. I just wanted to redo the splices and go from there with trouble shooting if that didn't fix it. I do recall that I took it back to Circuit City after the install when it failed, the repair person told me it was the foam they put in at the switches to keep the illumination from " leaking " out around the switch, that was on the passenger side. He " took out the foam " . That didn't sound right at the time but the system worked after I took it to him so I didn't give it much further thought. Then of course it failed again and that's what I just fixed since we have no more Circuit City :>)

I took some pictures of the splices and how they looked after I took the black electrical tape off of them. I'll post them but I have to retrain myself how to do it here, I know I did it once in the past but that was a " long time ago " :>) I want to post them like you posted yours rather than from a " photo Bucket "

After reinstalling the " Window Inner Mounting Panel " I would recommend that one doesn't remove it unless you absolutely have to . I guess if we did it very often it wouldn't be such a deal but for me it wasn't that simple to reinstall.

My next project is to find out why the interior lights no longer work. I'll live with the daytime driving lights not working, that's much less load on the alternator :>) I can also live without the seat adjuster circuit, it hasn't worked from the day I purchased the truck, I can live without that also :>) I forgot to mention the " center " cigarette lighter, there are 2 others that work :>)

Jerry

[ginger743]

Hi Dennis ,

Here is a link to a Photo Bucket of the splices and Schematic. I uploaded all of the photos that I took. The first photos that you see are after I reworked the splices with Butt Splices , crimped , soldered and covered with Heat Shrink Tubing. I dressed them after I shot the photos. Keep in mind, the person that did the splices had very little room to work, after breaking into the Harness , very little wire to work with. My rework was done after I pulled the door panel and pulled the harness further out .

Jerry

An amazing piece of work , those splices !!

Doing work like this should get a person fired real quick !!!!

http://s1353.photobucket.com/user/je...Splices?page=1

The wires with the color stripes go to the Alarm Relay Module that's in the kick Panel. They are spliced in series with the solid color Blue and White OEM Door Lock Wires.