Greg Smith Power door locks writeup PRE-1991

[XJEEPER]

I want to do this today and need the article that was posted on the OEM forum sometime ago. HELP!
XJEEPER

[Greg Smith]

Here is a current version of the writeup.

Power Door Lock Fix for Reluctant Locks on Pre 1991 Jeep Cherokees
(for post 90 models with a similar problem I woud check the relays in the passenger side kick panel)

The Problem:

Some (usually not all) of the power door locks stop working, or more commonly work inconsistently on the lock and/or unlock position. The problem usually starts when the Jeep gets older and the locks become stiffer. Cold weather seems to cause the most problems. The rear hatch and rear doors seem to the most troublesome since they are on the end of the circuit and experience the largest voltage drop.

The Cause:

The cause is a design flaw which causes a loss of 2 volts. As the Jeep gets older and the locks become stiffer and the connections develop some resistance the amount of voltage that gets through the system is no longer enough to work the power locks near the end of the circuit. With the pre 1991 wiring all the power for the power door locks passes through the passenger door lock switch regardless of whether you trigger that switch, the driver’s side door switch or the remote keyless opener (if you have it). Power leaves that switch going to the door locks through the tan wire for unlock and the light green wire for lock.

The power goes from the passenger door switch to a splice in that door for the power lock in that door and then goes out the door and into the kick panel in front of the door on the passenger side. By the time the power gets to the kick panel it has lost about 2 volts. I replaced my passenger side switch suspecting a bad switch but still lost 2 volts out of the switch. I then did a full continuity and resistance test on the switch per the factory service manual and found no problems. I have never figured out why this happens but apparently Jeep could not either since they changed the wiring starting in 1991 to compensate for this problem. (Note the wiring change can be done like the post 1990 models but the fix I provide below is a lot easier in my opinion.) After the now lower voltage gets to the passenger side kick panel it goes under the carpet and over to the driver’s side and hits a master splice under the front floor carpet for the wires going to the driver’s side front and rear doors and the passenger side rear door. I unwrapped the tape around the splices and checked all the splices and they were clean and tight. Then I measured the voltage at the remaining power locks. By the time the voltage gets through the master splice is loses another 2+ volts and is not enough to power the locks consistently when they become stiff from old age or cold weather.

The Fix/Repair:

First make sure you are getting around 12 volts of power to your passenger side door switch directly or when you trigger the lock or unlock switch from the driver’s side or by the remote. You can test the voltage with a multi-meter at the wire harness connector in the passenger-side kick panel where the dark green, white and red wires go into the front door.

Assuming you have a full voltage supply to the passenger side switch, the fix is to install two relays in the passenger-side kick panel on the lock and unlock wires coming from the passenger side switch. The relays will increase voltage back up to 12 volts to compensate for the loss caused by the passenger side switch. With the voltage increase provided by the relays, the voltage at the remaining power door locks is increased by approximately 2 volts, enough to power all the locks, even in cold weather. This of course assumes that no wiring problems exist from the splices to the door locks. If you still have a problem at a particular door lock measure the voltage and make sure it is over 9 volts. With my fix it should be closer to 10 and perhaps 9 at the rear hatch.

The relays to use are 5 blade, 12 volt, 30 amp minimum rated relays with blades marked 85, 86, 87, 87a and 30. These relays are the same as those used for the keyless remote relays found in the passenger-side kick panel so you may find them cheap at the bone yard. You can also find them in automotive electric supply stores. Look in the section that has lighting upgrade supplies. For an easier install it is also best to buy wiring sockets that fit the relays. Here is a link to partsexpress.com an online supplier that has relays and sockets at reasonable prices. I used 2 bosch relays # 330-070 and 2 sockets # 330-075 (although 1 dual socket 330-078 could be used I believe). http://www.partsexpress.com/webpage....oup_ID=31&SO=2

Here is how I did the wiring: I used the two 12v relays. They have 5 blades: 86 is trigger pwr from the passenger dr switch; 85 is ground; 87 is the new pwr source; 30 is the path to the lock and 87a is to ground (in this application). I cut the Lgreen and tan wire about 5 inches forward (toward the front of the Jeep) of the wire harness connector that connects the wires to the wires coming out of the passenger frnt dr. In this example I attached the tan unlock wire coming from the passenger frnt door to 86 and 85 to ground; 30 is attached to the tan wire going to the door locks; and 87a is to ground. I used the new 10 gauge pwr line I had previously run to the battery/starter relay post with a 30 amp inline fuse. You can take off pwr from a splice on the red pwr going into the passenger door instead. (The same approach is used for the lgreen wire using the other new relay for for the lock circuit.) The key to making this work was 87a to ground. When the lgreen or tan wire are not in pwr mode they provide ground path to ground through the driver’s side switch. With my new relays I substituted a new body ground instead. As a result I increased voltage and created new better grounds. The locks now all slam open and closed even in very cold weather. Hope this helps. At least 30 people I have heard from have done this mod with great success. Greg

[phred]

Quoting from Greg:

"For an easier install it is also best to buy wiring sockets that fit the relays. Here is a link to partsexpress.com an online supplier that has relays and sockets at reasonable prices. I used 2 bosch relays # 330-070 and 2 sockets # 330-075 (although 1 dual socket 330-078 could be used I believe)."


I used the dual socket but had to switch the red and yellow wires in the socket to get the wiring to work properly. Easy enough to get the connectors out by releasing the spring catch with a paper clip. It would be quicker to use the two separate sockets ... A few crimp connections later and my locks were slamming open and shut!

Thanks for the great fix to an annoying problem!!

[DIGITRUCK]

Originally Posted by phred

Quoting from Greg:

"For an easier install it is also best to buy wiring sockets that fit the relays. Here is a link to partsexpress.com an online supplier that has relays and sockets at reasonable prices. I used 2 bosch relays # 330-070 and 2 sockets # 330-075 (although 1 dual socket 330-078 could be used I believe)."


I used the dual socket but had to switch the red and yellow wires in the socket to get the wiring to work properly. Easy enough to get the connectors out by releasing the spring catch with a paper clip. It would be quicker to use the two separate sockets ... A few crimp connections later and my locks were slamming open and shut!

Thanks for the great fix to an annoying problem!!

Hey Greg,

Thx 4 the quick reply with regards to which end is which after you cut the tan and lite green wires. Will probably ck them this weekend. But here is another question... according to PHRED who also used the DUAL SOCKETS said he swapped the red and yellow wires to get it to work.

Could that be my prob if my earlier question is corrected or ok to begin with? I'm not in the garage now so I'm not even sure which blade went to which wire. If memory serves I think it was Yellow went to 87 and Red went to 85? Do you think if I just swap the connections (put 12V feed to Red and 87 to Ground instead of swapping out the wires on the socket) it will work or will it cause a 12V Short/Fire?

btw - My 10 Ga (30A Fused) Power wire is direct to positive battery terminal thru firewall and then split into 14 Ga to Yellow (87) on both Dual Sockets. The 14 ga is around 2 feet long on driver's side and 4 feet long on pass side. Do you think the 14 ga wire would present any probs in delivering enough current to the locks?

Hope I'm making sense.

Thx, Phil

[Greg Smith]

Originally Posted by DIGITRUCK

Hey Greg,

Thx 4 the quick reply with regards to which end is which after you cut the tan and lite green wires. Will probably ck them this weekend. But here is another question... according to PHRED who also used the DUAL SOCKETS said he swapped the red and yellow wires to get it to work.

Could that be my prob if my earlier question is corrected or ok to begin with? I'm not in the garage now so I'm not even sure which blade went to which wire. If memory serves I think it was Yellow went to 87 and Red went to 85? Do you think if I just swap the connections (put 12V feed to Red and 87 to Ground instead of swapping out the wires on the socket) it will work or will it cause a 12V Short/Fire?

btw - My 10 Ga (30A Fused) Power wire is direct to positive battery terminal thru firewall and then split into 14 Ga to Yellow (87) on both Dual Sockets. The 14 ga is around 2 feet long on driver's side and 4 feet long on pass side. Do you think the 14 ga wire would present any probs in delivering enough current to the locks?

Hope I'm making sense.

Thx, Phil

12 gauge would be much better. The 14 gauge limits your amps which is part of the problem on the original wiring. The colors of the wires on these sockets varies so the important thing is to only go by which hole in the socket and its respective color wire hooks up to which numbered post on the relay when inserted into the socket. You are going to have to verify it all and not rely on wire colors on the sockets vs colors that worked for others on the sockets they used. Good Luck. Greg

[ChipsXJ]

Originally Posted by Greg Smith

:
Here is how I did the wiring: I used the two 12v relays. They have 5 blades: 86 is trigger pwr from the passenger dr switch; 85 is ground; 87 is the new pwr source; 30 is the path to the lock and 87a is to ground (in this application). I cut the Lgreen and tan wire about 5 inches forward (toward the front of the Jeep) of the wire harness connector that connects the wires to the wires coming out of the passenger frnt dr. In this example I attached the tan unlock wire coming from the passenger frnt door to 86 and 85 to ground; 30 is attached to the tan wire going to the door locks; and 87a is to ground. I used the new 10 gauge pwr line I had previously run to the battery/starter relay post with a 30 amp inline fuse. You can take off pwr from a splice on the red pwr going into the passenger door instead. (The same approach is used for the lgreen wire using the other new relay for for the lock circuit.) The key to making this work was 87a to ground. When the lgreen or tan wire are not in pwr mode they provide ground path to ground through the driver’s side switch. With my new relays I substituted a new body ground instead. As a result I increased voltage and created new better grounds. The locks now all slam open and closed even in very cold weather. Hope this helps. At least 30 people I have heard from have done this mod with great success. Greg

This worked exactly as described. That is once I re-read it. I reversed 86 and 30 and it did not work. Then I re-read and corrected MY ERROR then it worked perfectly.

Thanks Greg!

[Greg Smith]

Glad it worked for you. Enjoy!!! Greg

[ChipsXJ]

I found that I could protect the power wire that runs out to the battery lug by using a vacuum connector that I found lying on the ground at the local u-pull-it. here are a couple of pics:

Before:


just cut off the piece I needed to fit the hole I was drilling.


I drilled a hole through just below the antenna boot behind the right kick panel.


and another hole near the hood prop.


This brings the power wire out very close the battery lug and keeps things tidy.

Just my .02 cents worth.

[kemper]

Hello all! - In regard to Greg's writeup: I have an '86 that I have been trying to fix the locks on to no avail...first, inside the psgr door on this year jeep there is a splice for the tan and light green wires to the psgr door, the psgr rear door and to the rest of the doors/rear hatch. This is different than Greg's post of there being a master splice on the driver's side under the carpet..not the case here...hence there is no general wire harness connector once the wire bundel leaves the psgr door and enters the kick panel, but rather two sets of light green and tan wires, one set going to the left side of the car (and eventually rear hatch) and one set to the psgr side rear door. Anyway, I spliced the wires together to simulate Greg's general wire harness connector and undid the extra two splices on the inside of the psgr door. So, after I did this, I hooked up the circuit just as described by the post with the Part's Express parts, was able to operate the switch on the psgr door completely (lock/unlock both worked) again and the lock part worked on the driver's switch. So, I figured since the whole system was working much better, but not completely, I went ahead and redid some of my earlier crude splices (with good ones) and tried the system again. Well, the unlock works on the psgr door, but when I press the lock part of that switch I just here a clicking sound coming from the relays. Does anyone know what might be happening here? Any help would be much appreciated. Thanks

[UN-limited'89]

Hi there, Greg:
Took the jeep to a friends stero shop, to work on this issue over the weekend. follow the diagram, but I think I missed something in the process.
1) didn't had the multimer on hand so I didn't check the voltage.
2) hook the power to the relays from the current power source.

Would I need to find another power source and re-check the incoming voltage?

thanks.
but on the postive side, the process is very simple, and quick.

[FRAM]

I wanted to post this earlier. Great write up Greg. I installed this upgrade on my 90 XJ Limited with a rear drivers door that was sticking in cold weather. The install was a snap but in all fairness I was in the final stages of my alarm/remote start install so I was no longer green as I was about 7 relays in by that point.

Wow what a difference. I just tapped into the red near the lock relays which provides enough power for my XJ. The locks slam shut now. When I showed my installer friend he was all worried I going to wear out the locks sooner now. :lol:

So thank you very much for your time and energy.

Another ill-fated door lock system has been revised thanks to your great write up.

[burntkat]

any chance anyone haas a power window fix along similar lines?

[Greg Smith]

Originally Posted by burntkat

any chance anyone haas a power window fix along similar lines?

See my post on this subject on page 3 post number 45 in this thread. Good Luck. Greg

[kemper]

Originally Posted by Greg Smith

Here is how I did the wiring: I used the two 12v relays. They have 5 blades: 86 is trigger pwr from the passenger dr switch; 85 is ground; 87 is the new pwr source; 30 is the path to the lock and 87a is to ground (in this application). I cut the Lgreen and tan wire about 5 inches forward (toward the front of the Jeep) of the wire harness connector that connects the wires to the wires coming out of the passenger frnt dr. In this example I attached the tan unlock wire coming from the passenger frnt door to 86 and 85 to ground; 30 is attached to the tan wire going to the door locks; and 87a is to ground. I used the new 10 gauge pwr line I had previously run to the battery/starter relay post with a 30 amp inline fuse. You can take off pwr from a splice on the red pwr going into the passenger door instead. (The same approach is used for the lgreen wire using the other new relay for for the lock circuit.) The key to making this work was 87a to ground. When the lgreen or tan wire are not in pwr mode they provide ground path to ground through the driver’s side switch. With my new relays I substituted a new body ground instead. As a result I increased voltage and created new better grounds. The locks now all slam open and closed even in very cold weather. Hope this helps. At least 30 people I have heard from have done this mod with great success. Greg

Greg, from your initial writeup you have the new power going to 87, not 30. And you also have 30 going to wires going to the rest of the door locks, not 87. This is what I followed along with the rest of the above quotation...is your most recent post just reversed on accident? Thanks

[LifteDLife97]

Originally Posted by Greg Smith

Here is a current version of the writeup.

Power Door Lock Fix for Reluctant Locks on Pre 1991 Jeep Cherokees
(for post 90 models with a similar problem I woud check the relays in the passenger side kick panel)

The Problem:

Some (usually not all) of the power door locks stop working, or more commonly work inconsistently on the lock and/or unlock position. The problem usually starts when the Jeep gets older and the locks become stiffer. Cold weather seems to cause the most problems. The rear hatch and rear doors seem to the most troublesome since they are on the end of the circuit and experience the largest voltage drop.

The Cause:

The cause is a design flaw which causes a loss of 2 volts. As the Jeep gets older and the locks become stiffer and the connections develop some resistance the amount of voltage that gets through the system is no longer enough to work the power locks near the end of the circuit. With the pre 1991 wiring all the power for the power door locks passes through the passenger door lock switch regardless of whether you trigger that switch, the driver’s side door switch or the remote keyless opener (if you have it). Power leaves that switch going to the door locks through the tan wire for unlock and the light green wire for lock.

The power goes from the passenger door switch to a splice in that door for the power lock in that door and then goes out the door and into the kick panel in front of the door on the passenger side. By the time the power gets to the kick panel it has lost about 2 volts. I replaced my passenger side switch suspecting a bad switch but still lost 2 volts out of the switch. I then did a full continuity and resistance test on the switch per the factory service manual and found no problems. I have never figured out why this happens but apparently Jeep could not either since they changed the wiring starting in 1991 to compensate for this problem. (Note the wiring change can be done like the post 1990 models but the fix I provide below is a lot easier in my opinion.) After the now lower voltage gets to the passenger side kick panel it goes under the carpet and over to the driver’s side and hits a master splice under the front floor carpet for the wires going to the driver’s side front and rear doors and the passenger side rear door. I unwrapped the tape around the splices and checked all the splices and they were clean and tight. Then I measured the voltage at the remaining power locks. By the time the voltage gets through the master splice is loses another 2+ volts and is not enough to power the locks consistently when they become stiff from old age or cold weather.

The Fix/Repair:

First make sure you are getting around 12 volts of power to your passenger side door switch directly or when you trigger the lock or unlock switch from the driver’s side or by the remote. You can test the voltage with a multi-meter at the wire harness connector in the passenger-side kick panel where the dark green, white and red wires go into the front door.

Assuming you have a full voltage supply to the passenger side switch, the fix is to install two relays in the passenger-side kick panel on the lock and unlock wires coming from the passenger side switch. The relays will increase voltage back up to 12 volts to compensate for the loss caused by the passenger side switch. With the voltage increase provided by the relays, the voltage at the remaining power door locks is increased by approximately 2 volts, enough to power all the locks, even in cold weather. This of course assumes that no wiring problems exist from the splices to the door locks. If you still have a problem at a particular door lock measure the voltage and make sure it is over 9 volts. With my fix it should be closer to 10 and perhaps 9 at the rear hatch.

The relays to use are 5 blade, 12 volt, 30 amp minimum rated relays with blades marked 85, 86, 87, 87a and 30. These relays are the same as those used for the keyless remote relays found in the passenger-side kick panel so you may find them cheap at the bone yard. You can also find them in automotive electric supply stores. Look in the section that has lighting upgrade supplies. For an easier install it is also best to buy wiring sockets that fit the relays. Here is a link to partsexpress.com an online supplier that has relays and sockets at reasonable prices. I used 2 bosch relays # 330-070 and 2 sockets # 330-075 (although 1 dual socket 330-078 could be used I believe). http://www.partsexpress.com/webpage....oup_ID=31&SO=2

Here is how I did the wiring: I used the two 12v relays. They have 5 blades: 86 is trigger pwr from the passenger dr switch; 85 is ground; 87 is the new pwr source; 30 is the path to the lock and 87a is to ground (in this application). I cut the Lgreen and tan wire about 5 inches forward (toward the front of the Jeep) of the wire harness connector that connects the wires to the wires coming out of the passenger frnt dr. In this example I attached the tan unlock wire coming from the passenger frnt door to 86 and 85 to ground; 30 is attached to the tan wire going to the door locks; and 87a is to ground. I used the new 10 gauge pwr line I had previously run to the battery/starter relay post with a 30 amp inline fuse. You can take off pwr from a splice on the red pwr going into the passenger door instead. (The same approach is used for the lgreen wire using the other new relay for for the lock circuit.) The key to making this work was 87a to ground. When the lgreen or tan wire are not in pwr mode they provide ground path to ground through the driver’s side switch. With my new relays I substituted a new body ground instead. As a result I increased voltage and created new better grounds. The locks now all slam open and closed even in very cold weather. Hope this helps. At least 30 people I have heard from have done this mod with great success. Greg

will this work on a 1997?