Door Ajar sensors

[jr1under]

I'm going in circles chasing an issue in my 1999 5.4. Even after a hard reset, the scanner consistently shows B1318-Battery Voltage Low and B1323-Door Ajar Warning Lamp circuit failure. The battery is new, alternator is fine, and the lamps always turn on and off as expected so I removed the three most likely sensors, driver's door and the two in the liftgate, and brought them in to test.

The driver's door and liftgate door sensors are identical and test as expected, normally closed, normal being when the door is shut and the plunger is pushed in. However, the liftgate window sensor is a different part # and tests normally open, the circuit closes when the window is up and opens when the window is shut. I don't know if this is a problem or just how it's supposed to work and I'd appreciate hearing from someone who can explain.

 

[BlackBetty]

Also, I would check the other doors as well. Remember a coworker had a similar issue; his interior lights would not cutoff until they hit that “I’ve been on way to long” limit.

I ended up finding the rear driver door switch to be bad.

 

[jr1under]

Also, I would check the other doors as well. Remember a coworker had a similar issue; his interior lights would not cutoff until they hit that “I’ve been on way to long” limit.

I ended up finding the rear driver door switch to be bad.

How did you determine it was bad? Was it obvious like the push pin was sticking or the wiring/connector damaged? So far, I've checked the driver door switch and the two in the liftgate with no indication of trouble.

Moving on to the other three doors as suggested. I know there's a good chance this is a GEM issue but that's a problem I can't fix so I'm hoping it'll turn out to be a bad switch.

 

[Hamfisted]

If you have the ForScan app and a laptop, you can select the door and tailgate PIDs and have an assistant go around the truck and open and close the doors / tailgate and watch the response in ForScan to see if everything is working properly. Circuits, switches, modules, etc ...

 

[Billme]

If you have the ForScan app and a laptop, you can select the door and tailgate PIDs and have an assistant go around the truck and open and close the doors / tailgate and watch the response in ForScan to see if everything is working properly. Circuits, switches, modules, etc ...

You just can’t replace Hamfisted

 

[jr1under]

If you have the ForScan app and a laptop, you can select the door and tailgate PIDs and have an assistant go around the truck and open and close the doors / tailgate and watch the response in ForScan to see if everything is working properly. Circuits, switches, modules, etc ...

No laptop but how about an iPad with the ForScan Lite app and a compatible scanner? Haven't used this combo enough to know if it's capable of those PIDs but I'll find out.

 

[jr1under]

The story so far...my 99 EB consistently reports a B1323-Door Ajar Warning Lamp circuit failure. Not the most urgent problem but I still want to understand what's going on. I suspect it's a GEM problem but testing that requires gaining access to the GEM which is not something I'm going to attempt for the first time. So trying to eliminate the other possibilities.

I removed and tested the six door ajar sensors and found zero signs of trouble. No corrosion, connectors full of grease, plungers not sticking - only point of interest was the liftgate window switch is NO while the rest are NC. But still the B1323.

So I spent some time learning to use FORScan Lite on an iPad, connecting via an OBDLink MX+ scanner. One of the pictures shows all the tests(PID's ?) I could find for door ajar status. The values changed as expected when the doors opened and closed.

All this involved a lot of battery disconnect/reconnect cycles. After each one, I'd take a short drive and then rescan and I noticed a pattern - the B1323 was constant but usually there was another seemingly random code like these:

B1318 Battery voltage Low
B1410 Left Front Power Window Motor circuit failure
B1325 Door ajar lamp battery short
C1726 Rear pneumatic fault
B1352 Left Front Temperature Damper Motor
---------
P0500 Vehicle Speed Sensor 'A' Circuit

They come and go and I think they're just ghosts in the machine. The P0500 would be a concern had I not been following Billme's thread on that topic. Instead, my conclusion is that the GEM is exhibiting erratic behavior as it ages, a topic some of us are familiar with. And unless it gets worse, I'm ignoring it.

 

[jr1under]

Add "B1450 Wiper select switch circuit failure" as another random code that's paired with B1323.

 

[Billme]

Instead, my conclusion is that the GEM is exhibiting erratic behavior as it ages, a topic some of us are familiar with. And unless it gets worse, I'm ignoring it.

I would like to ignore it, but it definitely changes how my transmission shifts, and the power used to get rolling.. In my case, when it’s not right, I feel I’m mashing the gas more to get up to speed.. When it’s right, I can barely touch the throttle and she goes quick, telling me the TC is not fully engaged.. Most wouldn’t notice it..
Can’t wait to hear from the transmission shop..

 

[jr1under]

I would like to ignore it, but it definitely changes how my transmission shifts, and the power used to get rolling.

Mine's a lot easier to ignore than that!
After testing and experimenting for months, I still think the codes I'm getting are ghosts in the GEM. Thought I'd isolated a battery drain on a couple of circuits but then discovered that testing idle current flow with a multimeter isn't as straightforward as it seems. After performing the tests correctly, the idle drain readings were an insignificant 50mA.

 

[jr1under]

Can’t wait to hear from the transmission shop..

I've followed your saga for a long time so I'm interested in what they have to say too.

 

[Billme]

I've followed your saga for a long time so I'm interested in what they have to say too.

By all means I will let you know .. They sure are taking their time hehe

 

[jr1under]

Earlier in this thread, Hamfisted mentioned using FORScan to gather more detailed data on my door-ajar problem. I already had FORScan Lite(iOS) and an OBDLink MX+ scanner but had never tried them, instead using an Ancel scanner and then later BlueDriver. Turns out FORScan provides way more info than I knew was available for a Gen1. The picture shows some of the PID's available just for the transmission.

 

[Billme]

Earlier in this thread, Hamfisted mentioned using FORScan to gather more detailed data on my door-ajar problem. I already had FORScan Lite(iOS) and an OBDLink MX+ scanner but had never tried them, instead using an Ancel scanner and then later BlueDriver. Turns out FORScan provides way more info than I knew was available for a Gen1. The picture shows some of the PID's available just for the transmission.

Well, I could have used that for sure.. I was going to get that a while back, and just didn’t do it.. If that shop don’t get on it this week, I’m going to get it, and go another route.. Been there two weeks and hasn’t been moved yet

 

[Billme]

Let me give a final update.. The shop turned out to be very professional..After several days of driving , the PO500 came back.. Yeah, I know lol but my guy said Mr. Bill, I should have checked your alternator first thing.. So I got it back down there and he put the scope on it, and he found the problem.. The AC was spiking… He said get a new alternator and not a rebuild, so I ordered one and put it on.. Been driving a little over a week and I can’t make it give me a code..
No more low battery voltage, PO 500’s no ghost codes whatsoever..
This could have been the regulator, but I wasn’t taking anymore chances, and got a whole new one..
I didn’t realize how bad a shape that transmission was for as the clutches..I now know how what to look for.. These guys were great.. They were really liking this machine, and said it drives like it has just 50, 000 miles instead of 300, 000..
Anyway, on to the next fix

 

[jr1under]

Wow, the parallels continue - I'm replacing my alternator today. It left this life 10 miles from home on Sunday evening and I had to call a wrecker. Yesterday, I pulled out the old and bought a new new one, installing it now.

 

[Billme]

Wow, the parallels continue - I'm replacing my alternator today. It left this life 10 miles from home on Sunday evening and I had to call a wrecker. Yesterday, I pulled out the old and bought a new new one, installing it now.

I’m sorry to hear it, Jr1under but it is amazing we are paralleling with our problems..
I’ve been driving it the longest without a PO 500, and before I wrote the last info last nite, I said as soon as I say all this, this po500 will come back.. Guess what I just checked? It just came back..
I guess I will get back with the shop, and see if they will pursue this, otherwise the only thing I know to do is have the GEM rechecked, or maybe the PCM, or there is still a short somewhere.. I’m determined to find the answer..
Hamfisted? Any chance you can add to this?

 

[jr1under]

I said as soon as I say all this, this po500 will come back.. Guess what I just checked? It just came back..

Obviously the shop disconnected the battery at some point...does it always take x amount of miles or trips or time before the P0500 comes back? Would you gain any useful info from clearing codes, doing a power reset, and keeping track of what happens until the code reappears?

 

[Billme]

Obviously the shop disconnected the battery at some point...does it always take x amount of miles or trips or time before the P0500 comes back? Would you gain any useful info from clearing codes, doing a power reset, and keeping track of what happens until the code reappears?

It took much longer for the codes to show up.. I’m going to check the new harness on the differential and see if they extended it pass the mounting point on the body.. If they didn’t, the break could still be there… We monitored the speed testing and it was normal.. I need to let home compare the AC again against the new alternator too..
I drove it above highway speed and do have a slight shake, hence makes me want to check the harness again, or the tone ring may be damaged, but then again, the signal didn’t miss a beat going to the ABS module according to the tech..This means the GEM module is sending a signal to the PCM.. This is making my head hurt lol