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1995 Esprit S4S
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Discussion Starter #1
So I ran Espritmon and did the ABS diagnostics. It came up with "Low pressure Accumulator". My ABS Light is flashing. When I step on the brake, I can hear the pump come on but the relay under the hood is going crazy, switching the pump on and off rapidly and randomly. Do you think this is a bad pressure switch?

Bill
 

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No, it's more than likely you need a new accumulator and that is much better for you than the pressure switch. ;)
 

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What is the trouble code number?

Chances are you need a new accumulator. Part number 25528382, pick one up from Rock Auto.
 

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1995 Esprit S4S
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206 Posts
Discussion Starter #5
update

So I replaced the accumulator... no change.. still got a flashing abs light, espritmon says the problem is low pressure accumulator and when I step on the brake, the pump activates but shuts off and turns on randomly.... Any other ideas? Maybe ill take apart my pressure switch and clean it... but im only guessing at this point. The problem seems to be electrical.
 

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Definitely take the switch out and clean it, can't hurt.

When was the last time the whole system was flushed and bled (per the manual)?

As Sanj asked, what number is the trouble code?
 

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Did you reset the codes after you changed the accumulator? If not, do so (press 't' in EspritMon while in the ABS screen) and see which codes comes back.
 

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1995 Esprit S4S
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206 Posts
Discussion Starter #9
Did you reset the codes after you changed the accumulator? If not, do so (press 't' in EspritMon while in the ABS screen) and see which codes comes back.
Ill do that this afternoon and repost. thanks!

Bill
 

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To perform further troubleshooting, you are probably going to need a pressure gauge test set designed for this system, as well as the ABS manual. The gauge sets are pretty readily available on eBay, search for Kent-Moore J-37118. Note that one of the fittings (the female one you screw the accumulator into, IIRC) may need modification to seal properly.

I'm also not sure how much capability EspritMon offers compared to the Tech-1, but you should hopefully be able to perform some of the tests listed. You may wish to try the switch cleaning procedure, as well as verifying that the pump relay has good connectivity.


 

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More info:

E. PUMP OFF TIME TOO SHORT
Symptom: Pump is off for too short a period of time causing pump to cycle frequently.
Possible Causes: Excessive internal leakage; low precharge accumulator; leaking solenoid(s); damaged master cylinder/booster assembly.

1. Turn off ignition. Depressurise the accumulator.
WARNING: Ensure the accumulator is fully depressurised (apply brake pedal hard and release at least 40 times with ignition off) before removing accumulator.
Remove accumulator and install pressure gauge T000T1112. Install accumulator on pressure gauge adaptor.

2. Turn ignition on to let pump run for 15 seconds. Turn ignition off and apply the brake pedal hard and release up to 40 times to de-pressurise accumulator.

3. Observe pressure gauge while turning on ignition. Is there a sudden jump in pressure from 0 psi to 500 psi or more almost immediately after the ignition is turned on? (This initial jump in pressure is the amount of accumulator precharge). If not, the accumulator must be replaced because the precharge is too low.

4. Allow the system to pressurise until the pump shuts off. With ignition still on, determine the pump off time by moderately applying the brakes and holding the pedal in the applied position. The pump off time is the time between brake apply and pump run. (Pump run test may also be performed via 'Tech 1')

5. Refer to the chart below to determine whether the accumulator or master cylinder/booster assembly should be replaced. If pump off time is less than 50 seconds, check accumulator precharge. If accumulator precharge is less than 600 psi, replace the accumulator. If precharge is 600 psi or greater and the pump off time is less than the corresponding chart value, replace the master cylinder/booster assembly.
Accumulator Pump
Precharge Off-time
(psi) (seconds)
1200 60
1100 55
1000 50
900 45
800 40
700 35
600 30
Less than 600 Replace accumulator
 

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1995 Esprit S4S
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206 Posts
Discussion Starter #13
I appreciate all of your help. I have already replaced the master cyl. the pump, and the accumulator. The only thing left worth replacing is that allusive pressure switch. Lotus Marques is making a new batch so I think im going to just replace the one on my car. My reasoning is that by the time I purchase everything I need to do a proper diagnosis of the ABS system I could have replaced the switch and moved on. So ill let you all know how it goes when I get a new switch.

Thanks

Bill
 

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I appreciate all of your help. I have already replaced the master cyl. the pump, and the accumulator. The only thing left worth replacing is that allusive pressure switch. Lotus Marques is making a new batch so I think im going to just replace the one on my car. My reasoning is that by the time I purchase everything I need to do a proper diagnosis of the ABS system I could have replaced the switch and moved on. So ill let you all know how it goes when I get a new switch.

Thanks

Bill
Please let us know if you hear that the switches are avail. I cleaned mine and still having issues intermittently.

THanks!
 

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1995 Esprit S4S
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206 Posts
Discussion Starter #16
Please let us know if you hear that the switches are avail. I cleaned mine and still having issues intermittently.

THanks!
Well, I have been in contact with Steve at Lotus Marques. They have suspended production of their ABS Pressure switch due to a calibration issue they need to work out. No timeline to get one at this point but hopefully will be available again by the next driving season...
 

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1995 Esprit S4S
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206 Posts
Discussion Starter #17
Cleaned it

So this is a follow up post. I still do not have a replacement switch. I have confirmed that it is the switch because today I pulled mine out of the car and soaked it in a shot glass in 91% isopropyl alcohol. After reinstalling, I had no brake issues. Don't know how long it will last. I put some miles on the car and could not get it to act up.

Bill
 

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1995 Esprit S4S
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206 Posts
Discussion Starter #18
follow up post

here is my last follow up post. no issues since soaking the ABS pressure switch in alcohol. Breaks work great. I know the ABS is working because I used it today on some black ice. ;-)
 
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