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47RE no lockup when cold

Old 01-11-2019, 07:40 PM
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47RE no lockup when cold

Looking for suggestions on what to check next. Here is the situation:

1997 4x4 2500 with 47RE trans

I installed a Suncoast valve body in August, with all new electronics.
Every thing was fine until temps started getting cold (upstate NY). Now it wont lockup 4th gear until I drive 8 miles, and the engine is fully up to temp.
I put in a 190 degree thermostat and have the radiator and trans cooler blocked off. It made no difference. Engine warms up like normal, good heat in cab, temp gauge reads correctly.
Factory service manual says the thermistor (temp sensor) is in the Governor Pressure Solenoid. So I dropped the pan and replaced that, even though it was only a few months old. Made No difference.
I know it is temp related because it always starts to work at the exact same place in my morning commute, and it will continue working fine as long as it is warm.
This did not happen with the original valve body.
Suncoast told me there are two temp senors, where is the other one? (I thought the cylinder head coolant sensor is just for the gauge, is this correct?) My gauge reads correct.
Any suggestions on what else to check?
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Old 01-15-2019, 03:20 PM
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This is a downloadable factory manual for a '96 - sorry, I don't have a link for a '97, but you can find the '97 manual at Geno's Garage. As far as I know, '96s and '97s are pretty much the same (disclaimer of your choice here...). I'd look through that manual and see what you can find on transmission temperature sensors - I'm only aware of one on my '96. If Suncoast says there are two, I'd ask them where the other is. If there is a relationship with an engine coolant temp sensor, it "should" be spelled out in the FSM. You might also see if you can find an ATSG manual for the 47RE and see what it says. Monitoring trans temp with a scan tool could be a good idea, but it's a toss-up as to whether the scanner can correctly read that - I have a SnapOn Modis that says my 47RE trans temp is 14,000+ degrees (always) but my ancient OTC Enhanced Monitor reads it just fine... If you read up in the FSM on how the sensor works, perhaps you could monitor it with a multimeter, long test leads, and backprobes. That won't tell you what temp the PCM thinks it is, but could give you insight as to whether there is a fairly steady change in signal. Also, consider checking continuity/resistance between internal trans connector, external connector, and PCM - maybe something's interfering with the connections and it doesn't go away until a certain temperature is reached
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Old 01-19-2019, 07:15 PM
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Thanks for the suggestions.
I already have the FSM for 1997.
Its says the " PCM prevents engagement of the converter clutch and overdrive clutch when fluid temp is below 50 degrees (F)."
It also says:
The conditions under which a shift to fourth will not occur are:
Overdrive switch off
Trans. fluid temp. below 50 or above 121 F
Shift to third not completed
Vehicle speed too low for 3-4 shift
Battery Temp. below -5 degrees F


So I suppose it is possible that the battery temp sensor is faulty. I will test that.
Suncoast couldn't offer any help other than telling me I need to put it on a scanner.
I dont have a scanner and always do all my own work on my vehicles...what scanner do I need and is it affordable for a DIY situation?
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Old 01-21-2019, 06:41 AM
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Could easily be the trans fluid temp sensor or it's wiring being faulty.. Or maybe your trans is efficient enough to need that time to get up to the min 50F to allow OD and LU.
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Old 01-21-2019, 03:25 PM
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As mentioned earlier, you may need to check in-pan trans wiring - also check and clean any connectors in the electrical path. Make sure all connectors are tight.

Just to be sure, you are using the liquid/liquid heat exchanger that sits under the turbo?

For scan tools, some people on a certain garage-related forum swear by Foxwell and some swear by Autel (depends on your price sensitivity). There's also Innova (easily available at local parts chains or online) and Actron, and AutoEnginuity (PC based) as other scan tool possibilities. Looks like all have multiple models with varying levels of capability (bi-directional or not, OBD2 only or OBD1 & OBD2, etc). I think harbor Freight even has a scan tool. I'd look for something easily returnable, in case it gives you way-out-of-reason readings. There isn't much on our trucks that can be controlled from a scan tool (the bi-directional aspect - though the charging system is a good example), but I'm sure you have other vehicles that have functional tests where you could benefit from a bi-directional scan tool
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Old 01-21-2019, 04:26 PM
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All the electronics in the pan are new.
I have tried two different temp sensors, both behave exactly the same.
I never had this problem in past winters, so trans efficiency cant be the problem.
Truck is 100% stock except for the Suncoast Valve body, so yes, I have the heat exchanger.
Im having a hard time imagining an electrical connection that only works when warm, and always starts to work at exactly the same spot in my morning drive. Its behaving more like a faulty sensor to me.

My 1997 is the newest vehicle I own. I have never needed a scan tool.
I can read error codes on the dash display. Currently there are no fault codes stored.
What scanner will allow me to read data from trans temp sensor and the PCM while its running? that is what Im looking for....some how I think the $69 Foxwell and Autel types wont do what I need, but correct me if Im wrong.

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Old 01-22-2019, 03:48 AM
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Originally Posted by APD View Post
All the electronics in the pan are new.
I have tried two different temp sensors, both behave exactly the same.
I never had this problem in past winters, so trans efficiency cant be the problem.
Truck is 100% stock except for the Suncoast Valve body, so yes, I have the heat exchanger.
Im having a hard time imagining an electrical connection that only works when warm, and always starts to work at exactly the same spot in my morning drive. Its behaving more like a faulty sensor to me..
It is not necessarily the sensor, but it can be somewhere in the wiring between the PCM and the sensor. A realtime readout of the PCM will show you if the trans temp as seen by the PCM is below 50F or not.
Even a faulty sensor or a faulty wire will not necessarily set a code. The reading can be wrong but still plausible and the PCM will think the trans is too cold (or too hot) and no code will be set.
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Old 01-22-2019, 07:30 AM
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Originally Posted by AlpineRAM View Post
It is not necessarily the sensor, but it can be somewhere in the wiring between the PCM and the sensor. A realtime readout of the PCM will show you if the trans temp as seen by the PCM is below 50F or not.
Even a faulty sensor or a faulty wire will not necessarily set a code. The reading can be wrong but still plausible and the PCM will think the trans is too cold (or too hot) and no code will be set.
Yes, that is why I asked for suggestions on which scanner to get. Got any suggestions on a specific model that will give the info I need?
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Old 01-22-2019, 11:09 AM
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I don't see any scanners from Foxwell for $60. The cheapest Foxwell scanners only come with software for one vehicle manufacturer/brand and you have to buy "authorizations" for additional manufacturers/brands separately - those additional-authorizations may be what you see for $60. If I was going with Foxwell, I'd probably go with the NT640 (if you have all US-manufacturer vehicles), the NT624 Pro (looks like the best for "all manufacturers"?) or perhaps the NT520 Pro with 2 manufacturers. Foxwell has a live-chat line, so you could consult with them and see what best suits your needs and possible future use (may as well get something you can use on the other vehicles in your family fleet - I would especially ask about ABS-bleed functions, as this is an area where many scanners have spotty coverage but is of great interest to a DIYer).

I would also look at Innova, and Bosch/OTC. Bosch bought OTC (at least the scan-tool segment), and has several scanners targeted at the DIY market. I'm sure something like an OTC3211 would more than suit the immediate need. I don't have any personal experience with any of these brands and specific tools, so I can't tell you exactly what you need - look at the descriptions, ask the manufacturers through their support channels, look on GarageJournal or other sites. Any of the OBD2 scanners should at least talk to your truck. This is just my own bias, but for an American-brand vehicle, I'd prefer Bosch/OTC (OTC has a history with pro-level tools). The reason I said earlier that you should buy through a channel where you can easily return it is in case it does not accurately read your trans temp. I have a SnapOn Modis (top-line pro tool, or was until fairly recently) and with the software version it has, it tells me my trans temp is 14000+ degrees (uh, right - my trans would be a puddle of aluminum)... Sometimes there are issues like that - one scanner manufacturer may not be so great with a particular vehicle manufacturer or vehicle or with certain data items or procedures. If anyone has personal experience with a scan tool that will accurately give trans temp for a '97 2500 Cummins, please chime in.

In general, look for something that has bi-directional control (look for: functional tests, ABS bleed, etc) and covers as many of your vehicles as possible - you probably won't be using it just on your truck.

Outside of the scan tool - if the FSM lists sensor-output values for different temperatures, you can get usable info on what's happening before the PCM by looking at sensor output with a good digital multimeter.
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Old 02-12-2019, 10:21 AM
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Just wanted to update my situation for others looking for info:

Problem is no longer temperature related (maybe never was). Now I have no Lockup in 4th gear at all.
All other shifts are normal, 3rd gear lockup works fine.
I have run the vehicle on a scanner and all the shifts occur normally, and the PCM is calling for Lockup when it should. Trans temp is fine.
I used the bi-directional testing of the scanner to confirm that the signal is reaching the transmission.
I checked the resistance of the solenoids at the transmission connector and got 35 ohms.
My TPS is new and checks out fine on the scanner.

From what I know now, everything seems to point to a problem with the valve body itself, not the electronics (Locks up 3rd gear but not 4th, So TCC solenoid is working).

I took a chance and bought a NT520 foxwell scanner and Im pleased with it. If you're looking for a scanner, this will measure:
Intake air temp/volts
Transmission fluid temp/volts
TPS voltage
TPS %
Battery Temp
Battery Volts
3-4 Shift solenoid status
OD Solenoid status
TCC solenoid Status
Governor Pressure Solenoid status
Governor pressure PSI
OD OFF button status
Engine RPM
Brake switch status
Vehicle speed
Transmission output sensor
Engine coolant temp (not accurate, may work on newer models)
Oil pressure (not accurate, maybe works on newer models)
There are many other things it will measure for gas engines and newer models as well, but these are the ones pertinent to my truck and transmission problem
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Old 02-12-2019, 03:49 PM
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Thanks for the update - I'm glad you were able to find a scanner that is working for your situation, and that it helped you delve deeper into your issue. Note that there is a "refresh rate" when it comes to scanners - you can have issues such as TPS "drop outs" that may be missed by a scanner because it occurs between screen refreshes/snapshots. The best way to test something like the TPS is either a "graphing multimeter"/scope or a digital meter that can capture a "drop out" (perhaps one with a bar graph and very high scan rate?). With a GMM, you do a full sweep of the TPS through it's range of motion (several times) and watch the voltage graph for dropouts. Worn throttle bellcrank bushings can cause issues with the TPS, which could cause the PCM to not call for lockup. But you say that in OD, the PCM is calling for lockup when it should? And you can verify by RPM & other values that you're in OD as commanded? What kind of data values (including governor pressure) are you seeing when the PCM says you're in OD?
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Old 02-12-2019, 04:31 PM
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OK, now would be the time to install a lockup switch for testing.
You could differenciate between the PCM ordering lockup from the software side and not getting through to the hardware side from a failure in your valvebody.
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Old 02-12-2019, 07:54 PM
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Originally Posted by AlpineRAM View Post
OK, now would be the time to install a lockup switch for testing.
You could differenciate between the PCM ordering lockup from the software side and not getting through to the hardware side from a failure in your valvebody.
Yes I had that same idea, but I tested the wiring with the bi-directional scanner tests and a test light, confirming that the signal is reaching the connector at transmission. Also, the TCC clutch command from the PCM is the same in both 3rd or 4th, and 3rd is always working.
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Old 02-12-2019, 08:09 PM
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Originally Posted by texasprd View Post
. But you say that in OD, the PCM is calling for lockup when it should? And you can verify by RPM & other values that you're in OD as commanded? What kind of data values (including governor pressure) are you seeing when the PCM says you're in OD?
Yes, according to the scanner, the TCC and OD solenoids are being commanded at the proper time (48mph)
I didn't specifically look at GPS pressure when in OD. But whenever I did look at it, it was within normal range (<2psi IIRC). It would throw a code if it were out of range, and I've had two NEW GP sensors in this valve body with the same results.

Right now at 55mph, Im turning 2100 RPM's.....normally there should be one more big shift that drops RPM's down to about 1500-1600.
When I accelerate above 55mph, both RPM's and MPH seem to move together, so no indication that it slipping
If I push the OD OFF button at 55mph, I feel two shifts, which I presume to be dropping down to 3rd, and then 3rd gear lockup

The scanner I have will do real time graphing, but the scale is off and I haven't figured out how to adjust it. I think it may just be a gimmick on this scanner and not really usable graphing as there seems to be no way to adjust the scale to match the values I am monitoring.
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Old 02-12-2019, 08:37 PM
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Hey one more question:

What would happen if I used the scanner to send a command to lock the TC while idling in my driveway. Would I do any damage?
I assume if I was in D range, it would stall the engine?
What about in Neutral?
Would I do any damage?

It says to turn engine off before running that test, so I have always obeyed.
I was considering trying it as a final confirmation that TCC was locking when commanded by PCM.
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