Driving the other day , come to a junction went to brake , peddle went to floor and I almost **** myself. Gingerly I managed to get the old girl home but had to practically stand on the brake pedal. Knowing nothing nothing about car mechanics and having very little in the way of tools I went on you tube. I've fitted a replacement pump and relay but everything is still the same . The pump does not run and the dashboard is still lit up like a Christmas tree. There is no pressure on the brake pedal at all. To recap pump and accumulator replaced relay replaced. Can anyone HELP. Bear in mind I'm a thicko so it isn't going to be easy talking me through this . Thanks guys
Brake problem P38 Auto Diesel Auto
- Thread starter Paul vice
- Start date
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brianp38dse
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Is the fluid level ok, as nearly all the p38`s a suffering brake pipe corrosion at back over fuel tank, if fluid ok the master cylinders have been known to fail internally, if you bleed the system you must do it to the letter of the workshop manual (Rave )
tomcat59alan
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If you have little mechanical knowledge then for your, and more importantly other people's safety get it booked into a garage that has the required expertise. 
Datatek
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If the pump does not run, I suspect the pressure switch has failed, not uncommon. Any burning smell in the fuse box.
No burning smell . Where do I find pressure switch ?
Thanks for that , but I'm a pensioner and haven't got garage money in my possesionIf you have little mechanical knowledge then for your, and more importantly other people's safety get it booked into a garage that has the required expertise.
Fluid level is perfect
Datatek
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Near the end of the pump, if you have an ohm meter, pull the connector off and put the meter across the pins of the switch, it should read zero ohms. If it does, put the meter on DC volts and with the ignition on put the meter probes on the connector pins, you should have 12 volts. Report back what you find please.
I'm a pensioner too so I know how you feel.
Datatek
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So, check you have voltage at the connector with the ignition on.
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Check master fuse 3 40 amp and relay 17 the black relay.
Fuse 3 40 good relay changed for New one pump swapped for another still nothing
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That would then suggest the switch is duff as Keith intimated.
Just my luck two pumps both with duff switches , pretty nagged off because the guy I bought the replacement one off assured me it was running when he removed it from his p38. Hundred quid thrown away that I couldn't afford in the first place and still can't drive my car. Definitely think its time for scrap yard and sell the caravan and get used to using the bus pass
Datatek
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Don't give up so easily. Two duff switches seems unlikely, have you checked that power is getting to the switch as I suggested? Have you checked continuity at the switch? Never a good idea to buy parts until you really know what the fault is, the fault may well be elsewhere.
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That is power to motor from relay 17, but relay 17 will not be pulled to run motor if switch is duff. DO NOT connect direct to battery.
Thanks for that , any idea why there would be no power there
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- Preston Lancs.
Because the pressure switch is not working. Basically when pressure is low pressure switch completes a circuit to pull relay 17, when pressure is high it breaks that circuit and stops pump.
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- 19,307
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- Buckinghamshire, UK. ('95 DT)
Have we ruled out the brake switch? That has 2 contacts from memory and the second one needs to work to pull the power assist in?
