OddJack

So I got this code yesterday morning. What makes it difficult to diagnose is that the problem comes and goes and the car shifts fine, usually. The problem is if you keep the speed steady or try to accelerate sllowly on the highway you feel a pause, like the pause you see right before the transmission shifts, but it's just a pause, the shift doesnt appear to happen. And this happens several times. This morning I cleared the code and drove the car. It did the same thing but didnt flash the any codes. I parked, did some shopping and drove back home and it was all normal, no pause or hesitation. I thought it is engine related, but the code points to the transmission, "low pressure sensor"
The reason I say it's hard because on the search I did here on P1810 all of them had lost gears or had harsh shifting. Not in this case.

1998 Z28 with 42K miles on it.

Anyone else had this same issue?

bbond105

The correct way to diagnose your problem would be to monitor the Transmission Fluid Pressure Manifold Switch with a scanner. Assuring that the switch corresponds with whatever gear the trans shifter is in. If you don't have access to a scanner, you could roll the dice and replace the Transmission Fluid Pressure Manifold Switch. Thay can be purchased from Rock Auto for around $40. STANDARD MOTOR PRODUCTS part # PSA100 would be a good mid-level replacement.

OddJack

Thank you bbond,

I have a Innova 5610 scanner, is this the type that can be used for this purpose or is there an special type of scanner for TFP ?

bbond105

I don't know if that scanner will give you live data or not. Just plug it into the car a see what you can access.

I just did a quick search and the Innova website says that it will give you live Transmission data. So, there you go.

OddJack

I could not find any availability for Tranny fluid pressure monitoring on any scanner. It only monitors the temperature.
I am going to just buy the switch and see if it improves anything.

Y2K_Frenzy

I believe you need a pseudo high end scanner or tuning software & hardware to see ATF pressures etc.

OddJack

It's always the first drive that has that issue. It hasnt happened when I come back home. If it was the switch, would it be intermittent like this? Maybe it's the fluid.

bbond105

You don't need to read the pressures. You need to compare with the engine running what gear the scanner says the transmission is in to the gear that the shift lever is actually in. (Ex Shifter is in drive, but scanner says neutral, or shifter is in drive, but scanner says it is in 1st or 2nd).

Tranzman

Here is the ATSG P1810 diagnostic sheet. It may help you figure it out. I had one that would only command 2nd gear and the PSM fixed it.

OddJack

So changing the PSM fixed your problem?

I have now changed the TFPSA twice. The second time was because I found out there is a newer version of the switch with a plastic cover.

The car still surges slightly when over 60 mph and pauses, surges and pauses. In that service sheet, it says " If the car feels like it has a bad fuel filter in all gears except manual low it's TFPSA"

Well, it does feel like that. If you try to accelerate at above 60 mph, it behaves like it cant get enough fuel. But the switch is new.

bbond105

Have you checked the fuel pressure at that speed and load?

OddJack

No, I dont have the tools and havnt done it before.

I guess I have to take it to a Tranny guy. What makes it harder is its not doing it all the time. More likely to happen on the first drive in the morning.

But would fuel pressure set P1810 ? I have done a lot of reading and didnt see any fuel pressure related to this issue.

bbond105

No fuel pressure won't set a P1810 code, but who's to say there isn't two problems going on. I the symptoms that you air describing are not typical for a P1810 code.

OddJack

The car has no other problems. Even this problem is not there all the time. I drove it today, all normal. took it to a transmission shop. They took it for a spin with a scanner. They said this happens only in cold temperature but couldnt pinpoint why. They said 3 possibilities, something internal to the tranny, some wire connection problem, or some other sensor problem. Well, that didnt help much. I could figure that much myself.

See, the fuel pressure problem is very unlikely. The car has no hiccup if run on D gear. In D it will go up to 3rd gear an no matter how high the RPM no problem occurs.

OddJack

New information... the surging smooths out if the brake pedal is applied slightly.

I am looking at this two solutions:

Replacing shift solenoid valve

Or Fitzall TCC replacement

If the problem is more likely in colder condition, which one is more likely to solve the problem?

MaroonMonsterLS1

Sounds like what you're feeling is in the tq converter
Can be caused by a handful of things
You can throw some parts at it with the fitzall valve and a TCC solenoid...but I'd start by watching to see if TCC is being commanded on then off then on then off when you feel this surging
Lightly applying the brake will make it such that the TCC will not apply...hence your issue goes away

Has the 1810 returned?
If it has, you could possibly have a suspect harness causing issues. Are there any leaks from the harness connector? If you unplug it does it appear wet with oil inside?

OddJack

Thanks MaroonMonster,

Yes, the 1810 returns. If its the harness, why is it always in the morning first run and dependent on the temperature? I am going to check the harness. Is the the one on top of the tranny?

The car has only 43K miles.

Could you tell if Innova 5610 scanner can scan that TCC on and off live while driving?

If TCC is being commanded on and Off, what would be the issue?

MaroonMonsterLS1

I know nothing about that scanner.
You'll have to see what it's capabilities are but you'll want to check for TCC command and TFP Switch position. The TFP Switch doesn't show pressure, it just shows yes/no for any combination of the switches.
As stated by others...if the switch positions don't match the expected positions...that is when the code will pop up

Seems to me you have 2 separate issues. The code is separate from the "feel" of the surge would be my current assumption

OddJack

For future reference, there is a newer version of that part by AC Delco. There was a GM bulletin that said they added a plastic cover to protect against shorting the circuit by the debris.

ACDelco GM Original Equipment 24215111

Problem not solved yet. Trying cheaper fixes first. Replacing the TPS now.

I dont think 1998 models provide live Transmission info to any scanner, maybe the temp but not much else. If anyone has done it I would like to hear from them.

RPM WS6

iTrader: (3)

I received your PM but I can't really help you with the problem as I have no experience with P1810 nor it being associated with the problems you're experiencing. It's also possible that you have more than one issue happening here, as someone suggested above. With that said, I can offer some insight here:

Yes, 1998 models will show commanded/current gear in real time on a scanner. The data is there, I can see it with my ancient AutoTap software on my equally ancient IBM laptop. I've had this software for well over 20 years, it was prime equipment back then and still works just fine today. So the data is there, but you probably need something more comprehensive than what you currently have to retrieve it.