Would be easier to see the actual firewall configuration to see the reason why it might not be working at the moment.
If I were to presume that you dont have any ACL configured on the "dmz" interface of the ASA and that the "dmz" interface of the ASA is of lower "security-level" than the "inside" interface then you would have to configure an ACL and attach it to the "dmz" interface to both allow traffic out to the Internet from the "dmz" and also allow traffic that you need (for example ICMP) to the "inside".
In your software level you would not really need any NAT configurations between the "dmz" and the "inside" like it was in the older software levels so I would imagine that should not be the case.
You could also add ICMP Inspection to your configurations unless they are already present.
You should be able to check current "policy-map" configurations on the ASA with the following command
show run policy-map
Usually there is the default "policy-map" configuration and its usually attached globally which you can check with the command
show run service-policy
You should be able to either enter the following commands under the "policy-map" configurations
inspect icmp
inspect icmp error
Or try to insert the following old format commands
fixup protocol icmp error
If there is still some problems would really need to look at the actual configurations and probably take some "packet-tracer" outputs
For example
packet-tracer input icmp 8 0
In some cases its also good to check the actual destination hosts since they might be blocking the ICMP and not the firewall.
If I were to create an ACL that simply only allows ICMP from the DMZ to the INSIDE then that would mean that all other traffic would be blocked and I don't know what other traffic should be allowed.
If I were to presume the following information to start with
INSIDE = 10.10.10.0/24
DMZ = 192.168.10.0/24
Allow ICMP traffic from DMZ->INSIDE but block all other traffic in this direction
If you are using an existing ACL on the DMZ interface then this would have to be added to that ACL with the correct IP address information to allow the traffic.
If you have no ACL on the DMZ interface then if DMZ hosts can already connect to INSIDE then they should also be able to ICMP the hosts on the INSIDE provided that the INSIDE hosts reply to ICMP. Its possible the hosts software firewalls block that.
Without seeing any configurations its impossible for me to give any specific instructions.
is it possible to have th erule only allow one host on the dmz to ping the inside interface?
If I enter the command you suggested it looks liek that will enable for the entire interface. But if I only want a host on the dmz to ping a host inside I tried:
