Code P1698 No Bus from TCM

Tiny
JMNWORB
  • MEMBER
  • 1998 DODGE CARAVAN
  • 3.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 256,000 MILES
I keep getting a message that says P1698 No BUS message from TCM. This happens only when the dash lights go out intermittently. Still shifts gears but shifts are hard nearly feels like an old 350 turbo with a shift kit installed or how we used to remove the spring that would allow it to snap into gear giving your tires a chirp between first and second with a very stiff jolt into third. “One time the dashboard lights went out (only once) it happened and the vehicle would only switch from first to second and the rpm's jumped to about 6,000 before I noticed that it was not switching gears.” I powered it off restarted and it began switching gears again but that only happened once while the dash lights were out.

The tachometer works while the rest of the cluster quits including speedometer. All gauges will not work when the dashboard lights go out. The ABS illuminates when the dash lights go out. The check engine light only comes on if the lights have been out for some time approximately thirty miles or the third restart it illuminates.

If cruise control is activated and the dash lights go out the gas pedal slams itself to the floor for wide open throttle.

Everything else still works while this happens both front power windows, stereo, fan for defrost/AC/heat, horn, turn signals etc. The information center console works during this outage just fuel mileage estimate just reads nothing until the dash lights come back on.

The rear vent windows on both sides will not open or close whatsoever at anytime.

This may happen three times a week or could go an entire month and not do this but once.

(Keep in mind the transmission not shifting out of second gear has only happened on one single occasion).

What could this be TCM? BCM? Bad solder on speedometer control board? Speed phasers input and output are new and did not resolve issue.

The rear vent windows a total separate issue? Window control switch is new but did not resolve the issue.
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Friday, June 29th, 2018 AT 2:53 AM

10 Replies

Tiny
JMNWORB
  • MEMBER
New today as console gauges and lights came back on I pulled a new code of 1698 no collision information from TCM. Same code but different wording I assume it all means the same. Also, I noticed that whenever I turn the parking lights on and only the parking lights or parking lights with interior lights I get the PRND32L and total mileage wavy lights like the old night rider show and eventually they begin to flash on and off then back to the wave. I wonder if this is somehow connected to this transmission code I noticed if I touch the circular dimmer dial located on the dash panel and apply a slight bit of pressure left or right while in the second or third position I can make the dash lights repeat this wavy and flashing action. I will try to attach a short ten second video. I apologize for the music the all factory radio is playing clean music in the background. I do not know how to remove it.
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Friday, June 29th, 2018 AT 11:11 PM
Tiny
KEN
  • ADMIN
Okay this will be a problem with the TCM or the cluster. I suggest removing the TCM and looking for corrosion at the connectors and inside the TCM because it is in front its subject to water damage. Here is the location to get us started. Disconnect the battery first. Thanks for the video it helps!

Please report back

Cheers, Ken
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Saturday, June 30th, 2018 AT 12:23 PM
Tiny
JMNWORB
  • MEMBER
Update: over the past three days the cluster has been completely off. Usually it would just go out for fifteen to thirty minutes but always came back to life. Sometimes the speedometer would jump back and fort for a quick moment before it stopped working and throwing the code 1698. This time the cluster just went completely out all at once never coming back on and threw the 1698 code about ten miles later. Due to it staying off for approximately three hundred miles now I tried to reset the code via the scan tool and it will not reset due to the current continuing condition I suppose. Before I could also take off the battery cable and it would reset the entire condition (the code and resolve the issue) not this time. I had also noticed nearly anytime the vehicle was jacked up during the condition and code that it would also reset and begin working again. But not this time. All coincidences I suppose. I have moved all the wires around jiggling them and shaking them even took up the floor seals to enable me to get to the floor wiring and removed the rubber door noting to do the same with those wires thinking it may be a broken, loose wire due to the jacking the vehicle fix but I see nothing. I do not see any corrosion as of yet. I have been unplugging and re-plugging everything one at a time and utilizing 3M dielectric upon reconnecting. I will take your suggestion and remove the TCM and advise. Thanks for the response and help. I really appreciate it as I was nearly forced to take it to the dealership without your response.
One last note just thinking of TCM vs ECM vs BCM. The voltage output usually runs on most vehicles around a 14.2. This vehicle The most I am getting via the ECM output is 13.8 volts fully loaded. Could that be anything meaningful? I am positive the alternator and battery are both good. The voltage regulator is the ECM on this vehicle.
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Tuesday, July 10th, 2018 AT 1:33 PM
Tiny
KEN
  • ADMIN
Not really that is within spec. It sounds like it will be the TCM or the cluster itself has gone bad. I would try used units and see what happens you can find them on eBay.

Please let us know what happens.

Cheers, Ken
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Friday, July 13th, 2018 AT 5:05 PM
Tiny
JMNWORB
  • MEMBER
Ken can or should I open this TCM up and look for loose or corrosion inside fairly easily without damaging the unit before I just start swapping parts out? Also, if I have to get a rebuilt unit does it have to be programmed to integrate it with the specific vehicle or is it just plug and play? Also, what is your opinion on the cruise control when the cluster goes out while the cruise is engaged it automatically moves the accelerator nearly all the way to the floor? That points more to the TCM in my head as well. But I had always been taught that there was no way possible for this to happen. It has been extremely hot here and I have no garage or even trees for that matter so I apologize if I have not gotten back to you quickly enough. When it is 100 degrees by 10:00am with the sun a beating down straight on you gives me limited time to get things done. FYI, I unplugged the TCM the connections were loose so maybe someone has had this out before I had a good two full turns to tighten both connectors prior to unloosing them and inspecting the ends. I saw nothing there. I will totally remove the unit in the morning.
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Saturday, July 14th, 2018 AT 12:04 AM
Tiny
JMNWORB
  • MEMBER
Update: Please see pictures. This TCM sits in a place that I have a hard time seeing it getting wet. Please do not take that I am questioning anyone I am just missing something I think or maybe I am looking at/taken the wrong part out. Many have said it gets wet from road rain and tires kicking it up. I can see an extreme overheat situation spraying and reaching it maybe and this TCM seems like it has a good seal. Unlike most others this is actually under the hood bolted to the inner fender well between the power steering Reservoir and radiator fill/overflow bottle. There are indeed two wires with black tape on them but I see no broken skin no wire probe marks or anything. It is a purple wire pinned out at number 43 and a white with Black stripe pinned out at number 4 on the TCM input plug. I have no idea or see any rhyme or reason. Wires and pins look in good working order and clean. See pictures. I need a suggestion if should I open this TCM up and if so what to look for please. It has tamper proof screws I guess saying stay out. This TCM unit is pretty clean and looks fairly new or within the past ten years anyway. I bought it second hand with a bad from timing cover and leaky valve cover gaskets. I just did not know I was getting into all the other stuff but I am in it for the hall now with a bit of your all s guidance. Wife has to drive this thing so I got to do something over the weekend to make it under its own power once again. Eagerly awaiting a response Thanks to all of your help.
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Saturday, July 14th, 2018 AT 5:05 AM
Tiny
JMNWORB
  • MEMBER
Here is with the cover off. I have no idea of what I am looking at besides it has a lot of clear rubber glue like waterproofing or heat proofing. It all looks fine to me. Please review the pictures of the inside. Is there a way to test this unit? What is my next step? I hope I am not giving you too much information. Electrical issues stump me much of the time and I try to learn by asking.
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Saturday, July 14th, 2018 AT 5:48 AM
Tiny
JMNWORB
  • MEMBER
Okay, I put this TCZm unit under my ring light and magnifying glass. I see no burn marks on the board. I see zero cracks in any of the solder. All contacts and connections appear to be good. I traced the bundle of wires from the harness elbow to the pins and I see no damaged wires by visually inspecting these. I spoke to the big three auto parts stores and each of them said there is no way to rule this part out. No way to check it other than visually. I have no idea why those two wires were taped together looked to be like it was some sort of marking to identify the two wires maybe. No damages. I am stumped.
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Saturday, July 14th, 2018 AT 7:07 AM
Tiny
JMNWORB
  • MEMBER
This all started with the gas gauge once it got below half a tank continuously going full to empty with the ping and gas light coming on and off. Fill it up and it would stop doing it until it got to just above the half way mark again. A week or so after that the dash cluster lights. This causing the no bus from transmission code. Did they not switch over to that cold solder somewhere in the mid to late 1990 s that was going to save the earth? Just wondering if in 1998 they just did not have the mixtures right for a cold solder. Just running through my head in how the boards would or could be stacked in the dash cluster at contact points if it is not similar to the stacking in a laptop computer. I am not the best at soldering I wonder if there could be a place that could hit all those solder points contact points with a better solder reasonable. Anyone?
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Saturday, July 14th, 2018 AT 7:39 AM
Tiny
KEN
  • ADMIN
Internally the IC's can be bad which there is no way to tell unless you are a rebuilder. The TCM looks good visually. I would try a used one and then the cluster if that doesn't work.
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Saturday, July 14th, 2018 AT 2:57 PM

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